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Abstract:

An epoxy resin composition, the epoxy resin composition including
components (A1) to (C1) described below, wherein the content of the
component (B1) is 8 to 20 parts by mass relative to 100 parts by mass of
the component (A1), and the content of the component (C1) is 12 to 110
parts by mass relative to 100 parts by mass of the component (A1):
component (A1): an epoxy resin; component (B1): a boron trihalide-amine
complex; and component (C1): rubber particles.

Claims:

1. An epoxy resin composition, comprising: components (A1), (B1) and
(C1), wherein a content of the component (B1) is 8 to 20 parts by mass
relative to 100 parts by mass of the component (A1), and a content of the
component (C1) is 12 to 110 parts by mass relative to 100 parts by mass
of the component (A1), wherein component (A1) is an epoxy resin,
component (B1) is a boron trihalide-amine complex, and component (C1) is
a rubber particle.

2. The epoxy resin composition according to claim 1, wherein the
viscosity at 30.degree. C. is from 0.1 Pas to 300 Pas.

3. The epoxy resin composition according to claim 1, wherein the particle
size of the component (C1) in a cured product of the epoxy resin
composition is 400 nm or less.

4. The epoxy resin composition according to claim 1, wherein the
component (C1) is a rubber particle comprising a butadiene rubber.

5. The epoxy resin composition according to claim 1, further comprising
component (D1), wherein component (D1) is a polymer which is compatible
with an epoxy resin composition comprising the components (A1), (B1), and
(C1), wherein the epoxy resin composition comprising component (D1) has a
characteristic of forming a phase separation structure when cured.

6. The epoxy resin composition according to claim 1, wherein the
component (B1) is a boron trichloride-amine complex.

7. The epoxy resin composition according to claim 1, wherein the
component (A1) is at least one selected from the group consisting of an
epoxy resin comprising an aromatic ring in the molecule, and
hexahydrophthalic acid diglycidyl ester.

8. An epoxy resin composition, comprising: components (A2), (B2) and
(D2), wherein a content of the component (B2) is 8 to 20 parts by mass
relative to 100 parts by mass of the component (A2), and a content of the
component (D2) is 1 to 50 parts by mass relative to 100 parts by mass of
the component (A2), wherein component (A2) is an epoxy resin, component
(B2) is a boron trihalide-amine complex, component (D2) is a polymer
which is compatible with an epoxy resin composition comprising the
components (A2) and (B2), and wherein the epoxy resin composition
comprising component (D2) has a characteristic of forming a phase
separation structure when cured.

9. An epoxy resin composition, comprising: an epoxy resin, an epoxy resin
curing agent which is a boron trihalide-amine complex, and a
thermoplastic resin; wherein the epoxy resin composition has a
characteristic of forming, when cured, a phase separation structure 1 in
which a phase of a cured product of the epoxy resin composition and a
phase of the thermoplastic resin constitute a sea-island phase separation
structure in the cured product, and a phase separation structure 2 which
is a sea-island phase separation structure, by taking the island
structure in the phase separation structure 1 as a sea structure.

10. The epoxy resin composition according to claim 9, wherein the content
of the epoxy resin curing agent is 8 to 20 parts by mass relative to 100
parts by mass of the epoxy resin, and the content of the thermoplastic
resin is 1 to 50 parts by mass relative to 100 parts by mass of the epoxy
resin.

11. The epoxy resin composition according to claim 9, wherein the sea
structure in the phase separation structure 1 is a phase of a cured
product of the epoxy resin, and the island structure is a phase of the
thermoplastic resin.

12. A tow prepreg, obtained by impregnating a reinforcing fiber bundle
with the epoxy resin composition according to claim 1.

13. A composite material-reinforced pressure vessel, produced from the
tow prepreg according to claim 12.

14. A composite material-reinforced pressure vessel, produced by filament
winding molding with a reinforced fiber bundle impregnated with the epoxy
resin composition according claim 1.

15. A tendon, produced from a composite material formed from the tow
prepreg according to claim 12.

Description:

TECHNICAL FIELD

[0001] The present invention relates to an epoxy resin composition which
has excellent storage stability, and produces a cured product having
excellent toughness and heat resistance.

[0002] The present application claims priority based on Japanese Patent
Application No. 2012-128322, filed in Japan on Jun. 5, 2012, and Japanese
Patent Application No. 2013-067300, filed in Japan on Mar. 27, 2013, the
disclosures of which are incorporated herein by reference.

BACKGROUND ART

[0003] In storage tanks for natural gas and hydrogen gas that are mounted
in movable bodies such as automobiles, pressure vessels having their tank
liners reinforced with a reinforced fiber composite material are utilized
in view of the lightweightness of the storage tanks. Regarding the
reinforcing fibers used therein, glass fiber, carbon fiber and the like
can be used. Among them, carbon fiber has high specific strength and is
highly advantageous in weight reduction of pressure vessels. Thus, carbon
fiber is suitably used in storage tanks for hydrogen gas where higher
pressure resistance performance is required as compared with storage
tanks for natural gas.

[0004] A pressure vessel reinforced with a reinforcing fiber composite
material is generally produced by filament winding molding (FW molding).
That is, FW molding is a molding method of paralleling one or plural
reinforcing fiber bundles, and during that process, continuously winding
the reinforcing fiber bundles around a rotating tank liner at a desired
tension and at a desired angle, while supplying a matrix resin to
impregnate the reinforcing fiber bundles with the matrix resin. For the
reinforcing fiber composite material, a tow prepreg obtained by
impregnating a reinforcing fiber bundle with a resin in advance may also
be used instead of the reinforcing fiber bundle. In this case, during the
process of paralleling one or plural reinforcing fiber bundles, supply
and impregnation of a matrix resin is not carried out, and the
reinforcing fiber bundles are wound around a rotating tank liner at a
desired tension and at a desired angle.

[0005] Regarding the matrix resin for the reinforcing fiber composite
material that reinforces a pressure vessel, epoxy resin compositions
having superior properties and good handleability are generally used. In
regard to FW molding, the matrix resin for a reinforcing fiber composite
material that reinforces a pressure vessel needs to be supplied to
impregnate reinforcing fiber bundles during the process. Furthermore,
also in the case of using a tow prepreg, it is necessary for the tow
prepreg to have satisfactory reelability, processability, and drape
properties. Accordingly, the matrix resin in the reinforcing fiber
composite material that reinforces a pressure vessel needs to have very
low viscosity compared with general epoxy resin compositions. From the
reasons described above, acid anhydrides are widely used as curing agents
for the epoxy resin composition (Patent Document 1, Patent Document 2,
and Patent Document 3). An acid anhydride is a low-viscosity liquid
curing agent, and can lower the viscosity of an epoxy resin composition.

[0006] However, an epoxy resin composition that has used an acid anhydride
has a short pot life, and definitely cannot be used in intermediate
materials such as a tow prepreg. Furthermore, even in a case in which an
epoxy resin composition using an acid anhydride has been supplied during
the process of FW molding, there is a need to diligently carry out
maintenance of many facilities such as a kiss roll or a die for supplying
a resin, a resin bus or a resin tank for collecting and holding a resin,
and a pump or a piping for transporting a resin. Thus, this has been a
cause for significantly deteriorating productivity.

[0007] Furthermore, when a solid curing agent such as dicyandiamide is
used, an epoxy resin composition having a longer pot life compared with
the case of an acid anhydride is obtained; however, there is a problem
that the viscosity of the epoxy resin composition is increased. Also,
when a solid curing agent is further used, voids are prone to be
generated in the reinforcing fiber composite material, and the voids may
cause deterioration of the performance of a pressure vessel, or the like
(Patent Document 4).

CITATION LIST

Patent Document

[0008] Patent Document 1: JP 8-219393 A

[0009] Patent Document 2: JP 2012-56980 A

[0010] Patent Document 3: JP 2012-63015 A

[0011] Patent Document 4: JP 2011-157491 A

DISCLOSURE OF THE INVENTION

Problem to be Solved by the Invention

[0012] Under such circumstances, an object of the present invention is to
provide an epoxy resin composition which has excellent storage stability,
produces a cured product having excellent heat resistance and toughness,
and can be suitably used in direct molding such as FW molding as well as
in intermediate materials such as a tow prepreg; a tow prepreg having
excellent reelability, processability and drape properties; and a
pressure vessel having high pressure resistance performance.

Means for Solving Problem

[0013] In order to solve the problems described above, the present
invention relates to the following.

[0014] [1] An epoxy resin composition, including components (A1) to (C1)
described below,

[0015] the epoxy resin composition having a content of the component (B1)
of 8 to 20 parts by mass relative to 100 parts by mass of the component
(A1), and

[0016] a content of the component (C1) of 12 to 110 parts by mass relative
to 100 parts by mass of the component (A1):

[0017] component (A1): an epoxy resin;

[0018] component (B1): a boron trihalide-amide complex; and

[0019] component (C1): rubber particles.

[0020] [2] The epoxy resin composition described in the above item [1],
wherein the viscosity at 30° C. is from 0.1 Pas to 300 Pas.

[0021] [3] The epoxy resin composition described in the above item [1] or
[2], wherein when the epoxy resin composition is cured, the particle size
of the component (C1) in the cured product is 400 nm or less.

[0022] [4] The epoxy resin composition described in any one of the above
items [1] to [3], wherein the component (C1) is rubber particles
containing at least butadiene rubber.

[0023] [5] The epoxy resin composition described in any one of the above
items [1] to [4], further including component (D1): a polymer which is
compatible with the epoxy resin composition containing the components
(A1) to (C1), and has a characteristic of forming a phase separation
structure in a cured product obtainable when an epoxy resin composition
including component (D1) is cured.

[0024] [6] The epoxy resin composition described in the above item [5],
wherein the component (D1) is a triblock copolymer or a polyamide
elastomer.

[0025] [7] The epoxy resin composition described in any one of the above
items [1] to [6], wherein the component (B1) is a boron trichloride-amine
complex.

[0026] [8] The epoxy resin composition described in any one of the above
items [1] to [7], wherein the component (A1) is at least one component
selected from the group consisting of an epoxy resin having an aromatic
ring in the molecule, and hexahydrophthalic acid diglycidyl ester.

[0028] the epoxy resin composition having a content of the component (B2)
of 8 to 20 parts by mass relative to 100 parts by mass of the component
(A2), and

[0029] a content of the component (D2) of 1 to 50 parts by mass relative
to 100 parts by mass of the component (A2):

[0030] component (A2): an epoxy resin;

[0031] component (B2): a boron trihalide-amine complex; and

[0032] component (D2): a polymer which is compatible with the epoxy resin
composition containing the components (A2) and (B2), and has a
characteristic of forming a phase separation structure in a cured product
obtainable when an epoxy resin composition including component (D2) is
cured.

[0033] [10] The epoxy resin composition described in the above item [9],
wherein the viscosity at 30° C. is from 0.1 Pas to 300 Pas.

[0034] [11] The epoxy resin composition described in the above item [9] or
[10], wherein the component (D2) is a triblock copolymer or a polyamide
elastomer.

[0035] [12] The epoxy resin composition described in any one of the above
items [9] to [11], wherein the component (B2) is a boron
trichloride-amine complex.

[0036] [13] The epoxy resin composition described in any one of the above
items [9] to [12], wherein the component (A2) is at least one component
selected from the group consisting of an epoxy resin having an aromatic
ring in the molecule and hexahydrophthalic acid diglycidyl ester.

[0037] [14] An epoxy resin composition, including an epoxy resin, an epoxy
resin curing agent which is a boron trihalide-amine complex, and a
thermoplastic resin,

[0038] the epoxy resin composition having a characteristic of forming,
when the composition is cured, a phase separation structure 1 in which a
phase of a cured product of the epoxy resin composition and a phase of
the thermoplastic resin constitute a sea-island phase separation
structure, and

[0039] further forming a phase separation structure 2 which is a
sea-island phase separation structure, by taking the island structure in
the phase separation structure 1 as a sea structure.

[0040] [15] The epoxy resin composition described in the above item [14],
wherein the content of the epoxy resin curing agent is 8 to 20 parts by
weight relative to 100 parts by mass of the epoxy resin, and

[0041] the content of the thermoplastic resin is 1 to 50 parts by weight
relative to 100 parts by mass of the epoxy resin.

[0042] [16] The epoxy resin composition described in the above item [14]
or [15], wherein the sea structure in the phase separation structure 1 is
a phase of a cured product of the epoxy resin, and the island structure
is a phase of the thermoplastic resin.

[0043] [17] The epoxy resin composition described in any one of the above
items [14] to [16], wherein the island structure in the phase separation
structure 2 is in a spherical form formed from a cured product of the
epoxy resin.

[0044] [18] The epoxy resin composition described in any one of the above
items [14] to [17], wherein the major axis of the island structure in the
phase separation structure 1 is 50 nm to 300 μm in length.

[0045] [19] The epoxy resin composition described in any one of the above
items [14] to [18], wherein the major axis of the island structure
(provided that when the sea-island structure is spherical, the diameter)
in the phase separation structure 2 is 10 nm to 100 μm in length.

[0046] [20] The epoxy resin composition described in any one of the above
items [14] to [19], wherein the thermoplastic resin is the following
component (D3):

[0047] component (D3): at least one block copolymer selected from the
group consisting of a S-B-M triblock copolymer and a M-B-M triblock
copolymer, in which the respective blocks represented by S, B and M are
linked by covalent bonding,

[0048] the block M is a homopolymer of polymethyl methacrylate, or a
copolymer containing methyl methacrylate at a proportion of at least 50%
by mass in terms of monomer relative to the total mass of all the
monomers, which is the feed amount of the block M,

[0049] the block B is a block which is non-compatible with the block M and
has a glass transition temperature of 20° C. or lower, and

[0050] the block S is a block which is non-compatible with the blocks B
and M and has a glass transition temperature higher than the glass
transition temperature of the block B.

[0051] [21] The epoxy resin composition described in any one of the items
[14] to [20], further including component (C3): rubber particles in an
amount of 12 to 110 parts by mass relative to 100 parts by mass of the
epoxy resin.

[0052] [22] A tow prepreg obtained by impregnating a reinforcing fiber
bundle with the epoxy resin composition described in any one of the above
items [1] to [21].

[0053] [23] The tow prepreg described in the above item [22], wherein the
reinforcing fiber bundle is a carbon fiber bundle.

[0054] [24] The tow prepreg described in the above item [23], wherein the
carbon fiber bundle is a carbon fiber bundle obtained by bundling 1000 to
70,000 filaments having a fiber diameter of 3 to 12 μm.

[0055] [25] The tow prepreg described in claim 23 or 24, wherein the
strand strength according to JIS R7601 of the carbon fiber is 3500 MPa or
more.

[0056] [26] A composite material-reinforced pressure vessel produced using
the tow prepreg described in any one of the above items [22] to [25].

[0057] [27] A composite material-reinforced pressure vessel produced by
filament winding molding using a reinforcing fiber bundle impregnated
with the epoxy resin composition described in any one of the above items
[1] to [21].

[0058] [28] The composite material-reinforced pressure vessel described in
the above item [27], wherein the composite material-reinforced pressure
vessel is a composite material-reinforced pressure vessel produced by
filament winding molding by winding the reinforcing fiber bundle
impregnated with the epoxy resin composition around a liner, and the
liner is made of a thermoplastic resin.

[0059] [29] The composite material-reinforced pressure vessel described in
the above item [27] or [28], wherein the reinforcing fiber bundle is a
carbon fiber bundle.

[0060] [30] A composite material-reinforced pressure vessel, formed by
coating the outer surface of a liner with a composite material layer, the
composite material layer being a layer formed using the tow prepreg
described in any one of the above items [22] to [25].

[0061] [31] The composite material-reinforced pressure vessel described in
the above item [30], wherein the liner is made of a thermoplastic resin.

[0062] [32] A tendon formed from a composite material, the tendon formed
using the tow prepreg described in any one of the above items [22] to
[25].

Effect of the Invention

[0063] According to the present invention, there is provided an epoxy
resin composition which has excellent storage stability and produces a
cured product having excellent toughness and heat resistance. This epoxy
resin composition can also be suitably used as a matrix resin in a
reinforcing fiber composite material. That is, this epoxy resin
composition can be used in general industrial applications such as sports
goods, automobiles, pressure vessels, airplanes, and tendons.
Particularly, this epoxy resin composition is characterized by exhibiting
high performance when used in a pressure vessel or a tendon. Also, this
epoxy resin composition is such that when used as a matrix resin in a
reinforcing fiber composite material, this epoxy resin composition can
also be combined with a reinforcing fiber and applied in an intermediate
material such as a prepreg or a tow prepreg. Particularly, when this
epoxy resin composition is applied to a tow prepreg, the tow prepreg has
satisfactory reelability from a bobbin and satisfactory processability,
and has excellent drape properties. The epoxy resin composition according
to the present invention can be used in molding that does not involve an
intermediate material, such as RTM molding (Resin Transfer Molding),
filament winding molding (FW molding), and pultrusion molding, or a tow
prepreg using the epoxy resin composition according to the present
invention can be used in filament winding, pultrusion molding or the
like.

BRIEF DESCRIPTION OF DRAWINGS

[0064] FIG. 1 is a schematic cross-sectional diagram illustrating an
example of a composite material-reinforced pressure vessel produced using
an epoxy resin composition according to an exemplary embodiment of the
present invention;

[0065] FIG. 2 is a graph diagram explaining the method for <Measurement
of glass transition temperature of cured product> in Examples of the
present invention, and is a graph diagram illustrating an example of
plotting log G' of the cured product (cured plate) against temperature
and determining (G'-Tg) from an intersection between an approximating
straight line for a flat region before the transition of log G' and an
approximating straight line for the region where transition of G' occurs;

[0066] FIG. 3 is an LSM photograph showing the state of a sea-island phase
separation structure of a cured product according to Examples of the
present invention; and

[0067] FIG. 4 is a diagram explaining the method for measuring the length
of the major axis of an island structure according to a third embodiment
of the present invention.

MODE(S) FOR CARRYING OUT THE INVENTION

First Embodiment

[0068] The epoxy resin composition according to a first embodiment of the
present invention is an epoxy resin composition containing component
(A1): an epoxy resin, component (B1): a boron trihalide-amine complex,
and component (C1): rubber particles. Hereinbelow, the various components
will be explained.

[0069] <Component (A1)>

[0070] Component (A1) is an epoxy resin.

[0071] Usually, the term epoxy resin is used as a name for one category of
thermosetting resins, and as a name for a category of chemical substances
called compounds having plural 1,2-epoxy groups in the molecule; however,
in the present invention, the term is used to mean the latter.
Furthermore, the term epoxy resin composition means a composition
including an epoxy resin, a curing agent, and optionally other
components.

[0072] The epoxy resin is not particularly limited as long as it is an
epoxy resin having two or more epoxy groups in the molecule; however,
from the viewpoint of imparting heat resistance to the cured product, it
is preferably at least one epoxy resin selected from the group consisting
of an epoxy resin having an aromatic ring in the molecule, and an epoxy
resin having an aliphatic ring in the molecule.

[0073] For the component (A1), it is preferable to use a bifunctional
epoxy resin having an aromatic ring in the molecule. When a bifunctional
epoxy resin having an aromatic ring in the molecule is used, the
viscosity of the epoxy resin composition of the present invention can be
adjusted to a range appropriate for handling. Furthermore, the mechanical
characteristics of a cured product of the epoxy resin composition of the
present invention can be adjusted to an appropriate range.

[0074] The "bifunctional epoxy resin" as used herein means a compound
having two epoxy groups in the molecule.

[0075] Examples of the aromatic ring for the bifunctional epoxy resin
having an aromatic ring in the molecule include a benzene ring, a
naphthalene ring, and a fluorene ring.

[0077] Among them, regarding the bifunctional epoxy resin having an
aromatic ring in the molecule, from the viewpoint that handling or
impregnation into a reinforcing fiber bundle is easily achieved because
the viscosity of the epoxy resin composition can be lowered, and that
heat resistance of a cured product is also excellent, a liquid bisphenol
A diglycidyl ether type epoxy resin having an epoxy equivalent of from
170 g/eq to 200 g/eq is particularly preferred.

[0078] Regarding the component (A1), a trifunctional or tetrafunctional
epoxy resin having an aromatic ring in the molecule may also be used.
When a trifunctional or tetrafunctional epoxy resin having an aromatic
ring in the molecule is used as the component (A1), handling of the epoxy
resin composition of the present invention and heat resistance of a cured
product of the epoxy resin composition of the present invention can be
adjusted to appropriate ranges.

[0079] Meanwhile, the "trifunctional or tetrafunctional epoxy resin" as
used herein means a compound having three or four epoxy groups in the
molecule. Examples of the aromatic ring for the trifunctional or
tetrafunctional epoxy resin having an aromatic ring in the molecule
include the same rings as the aromatic rings that may be carried by the
"bifunctional epoxy resin".

[0080] Specific examples of a trifunctional epoxy resin having an aromatic
ring in the molecule include a novolac type epoxy resin, an
N,N,O-triglycidyl-p- or -m-aminophenol type epoxy resin, an
N,N,O-triglycidyl-4-amino-m- or -5-amino-o-cresol type epoxy resin, and a
1,1,1-(triglycidyloxyphenyl)methane type epoxy resin.

[0081] Examples of a tetrafunctional epoxy resin having an aromatic ring
in the molecule include a glycidylamine type epoxy resin. Specific
examples include epoxy resins of diaminodiphenylmethane type,
diaminodiphenylsulfone type, and meta-xylenediamine type.

[0082] Among them, from the viewpoint that impregnation into a reinforcing
fiber bundle or handling is easily achieved because the viscosity of an
epoxy resin composition can be made relatively lower, and that heat
resistance of a cured product is also excellent, an
N,N,N',N'-tetraglycidylaminodiphenylmethane (TGDDM) type epoxy resin
having an epoxy equivalent of from 110 g/eq to 130 g/eq is particularly
preferably used.

[0083] The trifunctional epoxy resin and tetrafunctional epoxy resin
having an aromatic ring in the molecule are not intended to be limited to
these. Furthermore, two or more kinds of epoxy resins having an aromatic
ring in the molecule may also be used in combination.

[0084] Meanwhile, when a bifunctional epoxy resin and a trifunctional or
tetrafunctional epoxy resin are used in combination as the epoxy resin
having an aromatic ring in the molecule, the ratio of these resins is
such that at least one epoxy resin selected from the group consisting of
trifunctional and tetrafunctional epoxy resins:bifunctional epoxy resin
as a mass ratio is preferably 10:90 to 40:60, and more preferably 15:85
to 60:40.

[0085] If the content of the bifunctional epoxy resin is markedly large,
there may be a problem that it is difficult to impart relatively high
heat resistance that would result in a cured product having a glass
transition temperature of 150° C. or higher. On the contrary, if
the content of the bifunctional epoxy resin is markedly small, the cured
product may become noticeably brittle, the epoxy resin composition may
have relatively high viscosity, and there is a possibility of having a
problem that handling or impregnation into a reinforcing fiber bundle may
become difficult. Furthermore, if the content of the trifunctional or
tetrafunctional epoxy resin is markedly large, the epoxy resin
composition has relatively high viscosity, and there may be a problem
that handling or impregnation into a reinforcing fiber bundle becomes
difficult. On the contrary, if the content of the trifunctional or
tetrafunctional epoxy resin is markedly small, there may be a problem
that it is difficult to impart relatively high heat resistance that would
result in a cured product having a glass transition temperature of
150° C. or higher.

[0086] Regarding the component (A1), a bifunctional to tetrafunctional
epoxy resin having an aliphatic ring in the molecule may be used.
Examples of the epoxy resin include a compound in which an aliphatic ring
is condensed with an epoxy ring, and a compound in which a substituent
containing an epoxy group such as a glycidyl is bonded to an aliphatic
ring. The aliphatic ring for a compound in which an aliphatic ring is
condensed with an epoxy ring, is preferably an aliphatic ring having 6
carbon atoms, and specific examples thereof include a cyclohexane ring.

[0087] Examples of the compound in which an aliphatic ring is condensed
with an epoxy ring include 3,4-epoxycyclohexylmethyl carboxylate.

[0088] When these are used as the component (A1), it is preferable because
the viscosity of the epoxy resin composition can be lowered, and because
handling or impregnation into a reinforcing fiber bundle is made easier,
while the cured product has excellent heat resistance. Furthermore, it is
preferable because in a case in which a fiber reinforcing composite
material is produced, an effect of enabling appropriate adjustment of the
force of adhesion between the matrix resin and the surface of the
reinforcing fiber is obtained. Also, the aliphatic ring for the compound
in which a substituent containing an epoxy group such as a glycidyl group
is bonded to an aliphatic ring, is preferably an aliphatic ring having
six carbon atoms, and specific examples thereof include a cyclohexane
ring.

[0089] Examples of the compound in which a substituent containing an epoxy
group such as glycidyl group is bonded to an aliphatic ring include
hexahydrophthalic acid diglycidyl ester, and methyltetrahydrophthalic
acid diglycidyl ester. When these are used as the component (A1), it is
preferable because the viscosity of the epoxy resin composition can be
lowered, and because handling or impregnation into a reinforcing fiber
bundle is made easier, and in a case in which a fiber-reinforced
composite material is produced, the force of adhesion between the matrix
resin and the surface of the reinforcing fiber can be appropriately
adjusted. Furthermore, the epoxy resin having an aliphatic ring in the
molecule may be used in combination of two or more kinds thereof.

[0090] Also, an epoxy resin having an aromatic ring in the molecule and an
epoxy resin having an aliphatic ring in the molecule may be used in
combination as the component (A1).

[0091] As such, various epoxy resins can be used as the component (A1) of
the present invention; however, from the viewpoint of imparting heat
resistance to the cured product, an epoxy resin having an aromatic ring
in the molecule is preferred. Particularly, in 100 parts by mass of the
component (A1), the content of the epoxy resin having an aromatic ring in
the molecule is preferably 30 to 100 parts by mass, more preferably 40 to
100 parts by mass, even more preferably 50 to 100 parts by mass, and most
preferably 60 to 100 parts by mass.

[0092] Specifically, the epoxy resin having an aromatic ring in the
molecule is preferably a liquid bisphenol A diglycidyl ether type epoxy
resin having an epoxy equivalent of from 170 g/eq to 200 g/eq is
preferred, and it is preferable to use these at a content of 30 to 100
parts by mass in 100 parts by mass of the component (A1).

[0093] Meanwhile, the component (A1) may include an epoxy resin other than
those described above, to the extent that the effect of the present
invention is not impaired.

[0094] <Component (B1)>

[0095] Component (B1) is a boron trihalide-amine complex.

[0096] The boron trihalide-amine complex is preferably a complex composed
of boron halide such as boron trihalide or boron trifluoride, and an
organic amine. That is, the component (B1) is preferably a boron
trichloride-amine complex or a boron trifluoride-amine complex.

[0097] Specific examples include a boron trifluoride-aniline complex, a
boron trifluoride-p-chloroaniline complex, a boron trifluoride-ethylamine
complex, a boron trifluoride-isopropylamine complex, a boron
trifluoride-benzylamine complex, a boron trifluoride-dimethylamine
complex, a boron trifluoride-diethylamine complex, a boron
trifluoride-dibutylamine complex, a boron trifluoride-piperidine complex,
a boron trifluoride-dibenzylamine complex, compounds in which fluorine
atoms in these compounds are replaced with chlorine atoms, and a boron
trichloride-dimethyloctylamine complex.

[0098] Among these complexes, a boron trifluoride-piperidine complex and a
boron trichloride-dimethyloctylamine complex, which have excellent
solubility in an epoxy resin, enable composition containing these
complexes to have excellent pot life properties, and are industrially
easily available, can be preferably used.

[0099] Fiber-reinforced composite materials produced by using these
complexes as curing agents can obtain a force adequate for exhibiting
excellent tensile strength, in connection with the force of adhesion
between the matrix resin and the surface of the reinforcing fiber.
Furthermore, when a component (C1) is used in combination, due to an
enhancement of toughness of the matrix resin, fiber-reinforced composite
materials produced by using these complexes as curing agents can obtain
an excellent tensile strength manifesting effect. Moreover, when a
complex having excellent solubility in an epoxy resin, such as a boron
trifluoride-piperidine complex or a boron trichloride-dimethyloctylamine
complex, is used, generation of voids in the fiber-reinforced composite
material thus produced can be suppressed. Thereby, the fiber-reinforced
composite material can obtain an excellent tensile strength manifesting
effect.

[0100] When at least one selected from the group consisting of an epoxy
resin having an aromatic ring in the molecule, and a compound in which a
substituent containing an epoxy group such as a glycidyl group is bonded
to an aliphatic ring (particularly, hexahydrophthalic acid diglycidyl
ester) is used, it is preferable to use a boron trichloride-amine complex
as the component (B1) since curing can be achieved in a short time at a
lower temperature.

[0101] On the other hand, when a compound in which an aliphatic ring is
condensed with an epoxy ring is used as the component (A1), since curing
can be achieved in a short time at a lower temperature, it is preferable
to use a boron trifluoride-amine complex as the component (B1).

[0102] A preferred amount of incorporation of the component (B1) is
usually 8 parts by mass or more, preferably 9 parts by mass or more, and
usually 20 parts by mass or less, preferably 18 parts by mass or less,
and more preferably 17 parts by mass or less, relative to 100 parts by
mass of the component (A1) included in the epoxy resin composition of the
present invention.

[0103] That is, a preferred amount of incorporation of the component (B1)
is preferably from 8 parts by mass to 20 parts by mass, more preferably
from 8 parts by mass to 18 parts by mass, even more preferably from 9
parts by mass to 18 parts by mass, and particularly preferably from 9
parts by mass to 17 parts by mass, relative to 100 parts by mass of the
component (A1). When the amount of incorporation of the component (B1) is
significantly large or significantly small, there is a possibility that
heat resistance of the cured resin may be decreased.

[0104] <Component (C1)>

[0105] Component (C1) is rubber particles, and is incorporated for an
enhancement of toughness of the epoxy resin composition after being
cured. For the component (C1), at least one kind of rubber particles
selected from the group consisting of crosslinked rubber particles, and
core-shell type rubber particles in which, on the surface of crosslinked
rubber particles, a polymer different from the polymer that constitutes
the crosslinked rubber particles is graft-polymerized, is preferably
used.

[0106] In regard to the crosslinked rubber particles, the kind of rubber
is not limited, and for example, butadiene rubber, acrylic rubber,
silicone rubber, butyl rubber, NBR, SBR, IR, and EPR are used.

[0108] The "core-shell type rubber particles" are rubber particles in
which, on the surface of a particulate core component containing a
crosslinked rubber-like polymer as a main component, a shell component
polymer of a different kind from the core component is graft-polymerized,
and thereby a part or the entirety of the surface of the particulate core
component is coated with the shell component.

[0109] Examples of the core component that constitutes the core-shell type
rubber particles include the same components as those of the crosslinked
rubber particles described above. Among them, a crosslinked rubber-like
polymer composed of styrene and butadiene has a high toughness enhancing
effect and is preferable.

[0110] It is preferable that the shell component that constitutes the
core-shell type rubber particles is graft-polymerized to the core
component described above and is chemically bonded to the polymer that
constitutes the core component. The "chemical bonding" as used herein
means a bonding between atoms that form a molecule or a crystal by
binding atoms or ions. Particularly, chemical bonding as used herein
means covalent bonding formed as a pair of electrons is shared by two
atoms.

[0111] Regarding the component that constitutes such a shell component,
for example, a polymer obtained by polymerizing at least one selected
from the group consisting of an acrylic acid ester-based monomer, a
methacrylic acid ester-based monomer and an aromatic-based vinyl monomer,
can be used. When a crosslinked rubber-like polymer composed of styrene
and butadiene is used as the core component, a mixture of methyl
methacrylate, which is a (meth)acrylic acid ester, and styrene, which is
an aromatic vinyl compound, can be suitably used as the shell component.

[0112] Furthermore, it is preferable for the shell component to have
introduced therein a functional group that reacts with the component (A1)
constituting the epoxy resin composition of the present invention, in
order to stabilize the dispersion state. Examples of such a functional
group include a hydroxyl group, a carboxyl group, and an epoxy group, and
among them, an epoxy group is preferred. Regarding the method for
introducing an epoxy group, there is available a method of using, for
example, 2,3-epoxypropyl methacrylate in combination with the shell
component described above, and thereby performing graft polymerization to
the core component.

[0114] The rubber particles may be dispersed in the component (A1) using a
stirring machine, a roll mill or the like during the preparation of the
epoxy resin composition. However, when a master batch type rubber
particle-dispersed epoxy resin in which rubber particles are dispersed in
advance in an epoxy resin is used, the preparation time for the epoxy
resin composition can be shortened, and also, the dispersion state of the
rubber particles in the epoxy resin composition can be made satisfactory,
which is preferable. Furthermore, it is particularly preferable that the
rubber particles and the epoxy resin component are chemically bonded or
physically bonded.

[0115] Examples of such a master batch type crosslinked rubber
particle-dispersed epoxy resin include product name: BPF307 and product
name: BPA328 (manufactured by Nippon Shokubai Co., Ltd.), which contain
acrylic rubber; product name: MX-113 and product name: MX-416, which
contain core-shell rubber particles formed from a core component of a
copolymer of styrene and butadiene, and a shell component containing
methyl methacrylate and having a functional group that reacts with an
epoxy resin; product name: MX-156, which contains butadiene rubber; and
product name: MX-960 (manufactured by Kaneka Corp.), which contains
silicone rubber.

[0116] Meanwhile, for an enhancement of toughness of the epoxy resin
composition after being cured, and particularly for an effect of
increasing the burst pressure in the case of using a pressure vessel that
will be described below, the component (C1) is preferably rubber
particles containing butadiene rubber. That is, butadiene rubber
particles, or core-shell type rubber particles containing butadiene
rubber particles as a core component are preferred, and core-shell type
rubber particles containing butadiene rubber particles as a core
component are particularly preferred.

[0117] Furthermore, the particle size of the component (C1) in a cured
product of the epoxy resin composition of the present invention is
preferably from 50 nm to 400 nm, and more preferably from 50 nm to 300
nm. The particle size of the component (C1) in the cured product can be
measured by the following method.

[0119] An arbitrary area of 100 μm2 of the broken surface of a
test sample generated when the fracture toughness value of a cured resin
is measured according to ASTM D5045, is observed using SEM, and the
particle size of the component (C1) identified, or the diameter of a
recess from which the component (C1) has fallen off, is measured at any
arbitrary 10 sites. The average value is designated as the particle size
of the component (C1).

[0120] <When it is Difficult to Identify Particle Size of Component
(C1) by SEM>

[0121] A cured resin plate is immersed in dichloromethane, and the
component (C1) is eluted. An arbitrary area of 100 μm2 of the cured
resin plate from which the component (C1) has been eluted is observed by
scanning probe microscopy, the diameter of an identified recess from
which the component (C1) has been eluted is measured at any arbitrary 10
sites, and the average value is designated as the particle size of the
component (C1).

[0122] In order to adjust the particle size in a cured product to the
range described above, the particle size of the component (C1) in a cured
product of the epoxy resin composition can be controlled to the range
described above by using component (C1): rubber particles having a volume
average particle size of primary particles of preferably from
◯◯ nm to 400 nm, and more preferably from
◯◯ nm to 300 nm, dispersing the component (C1) in
the component (A1) using a stirring machine, a roll mill or the like; or
by preparing an epoxy resin composition using a master batch type rubber
particle-dispersed epoxy resin in which the component (C1) is dispersed
in advance in the component (A1). Meanwhile, the volume average particle
size of primary particles of the rubber particles can be measured with a
laser diffraction/scattering type particle size analyzer or the like.

[0123] A preferred amount of incorporation of the component (C1) is
usually 12 parts by mass or more, preferably 16 parts by mass or more,
and more preferably 20 parts by mass or more, and usually 110 parts by
mass or less, preferably 100 parts by mass or less, and more preferably
80 parts by mass or less, relative to 100 parts by mass of the component
(A1) contained in the epoxy resin composition of the present invention.

[0124] That is, a preferred amount of incorporation of the component (C1)
is usually preferably from 12 parts by mass to 110 parts by mass, more
preferably from 16 parts by mass to 100 parts by mass, and particularly
preferably from 20 parts by mass to 80 parts by mass, relative to 100
parts by mass of the component (A1).

[0125] When the component (C1) is included in a markedly large amount,
dispersion thereof into an epoxy resin may be difficult, or the epoxy
resin composition becomes highly viscous, so that there may be a problem
that handling or impregnation into a reinforcing fiber bundle becomes
difficult. On the contrary, when the component (C1) is included in a
markedly small amount, the enhancement of toughness of the epoxy resin
composition after being cured is insufficient, and there is a possibility
of having a problem that the effect of the present invention may not be
obtained.

[0126] <Component (D1)>

[0127] The epoxy resin composition of the present invention may further
include component (D1): a polymer which is compatible with the epoxy
resin composition containing the components (A1) to (C1), and has a
characteristic of forming a phase separation structure when an epoxy
resin composition including component (D1) is cured. Toughness of a cured
product of the epoxy resin composition is increased by the rubber
particles of the component (C1), but toughness can be further increased
by adding the component (D1).

[0128] Examples of the component (D1) include triblock copolymers such as
a M-B-M triblock copolymer and a S-B-M triblock copolymer (provided that
block M is a homopolymer of polymethyl methacrylate, or a copolymer
containing methyl methacrylate at a proportion of at least 50% by mass in
terms of monomer relative to the total mass of all the monomers, which is
the feed amount of the block M; block B is a polymer obtained by
polymerizing one or more monomers selected from butadiene, isoprene,
2,3-dimethyl-1,3-butadiene, 1,3-pentadiene, 2-phenyl-1,3-butadiene and
(meth)acrylic acid esters as monomers; and block S is a polymer obtained
by polymerizing one or more monomers selected from styrene,
α-methylstyrene and vinyltoluene); and polyamide elastomers.

[0129] A specific example of the triblock copolymer M-B-M may be a
copolymer composed of methyl methacrylate-butyl acrylate-methyl
methacrylate, and specific examples thereof include NANOSTRENGTH M22
(manufactured by Arkema S.A.) and NANOSTRENGTH M22N (manufactured by
Arkema S.A.) having polar functional groups.

[0132] For the component (D1), various polymers may be used singly, or two
or more kinds of polymers may be used in combination.

[0133] A preferred amount of incorporation of the component (D1) is
usually 1 to 50 parts by mass, and more preferably 5 to 25 parts by
weight, relative to 100 parts by mass of the component (A1) included in
the epoxy resin composition of the present invention. If the component
(D1) is present in an excessively large amount, the epoxy resin
composition becomes highly viscous, and there may be a problem that
handling or impregnation into a reinforcing fiber bundle may become
difficult. On the other hand, if the component (D1) is present in an
excessively small amount, there is a possibility that the effect of
incorporating the component (D1) may not be sufficiently obtained.

[0134] <Additives>

[0135] Furthermore, in the epoxy resin composition of the present
invention, additives such as inorganic particles such as silica powder,
AEROSIL, microballoons, antimony trioxide, alumina, and titanium oxide;
flame retardants such as phosphorus compounds; carbon particles such as
carbon black and activated carbon; defoamants; and wetting agents, may be
incorporated according to the purpose, to the extent that the effect of
the present invention is not impaired. The content of these additives may
be in an extent that the effect of the present invention is not impaired,
and the content is preferably from 0.1 parts by weight to 20 parts by
weight relative to 100 parts by weight of the epoxy resin composition
according to the first embodiment of the present invention.

[0136] <Epoxy Resin Composition>

[0137] The epoxy resin composition according to the first embodiment of
the present invention includes the following components (A1) to (C1) as
essential components:

[0138] component (A1): an epoxy resin;

[0139] component (B1): a boron trihalide-amine complex; and

[0140] component (C1): rubber particles.

[0141] Furthermore, the epoxy resin composition according to the first
embodiment of the present invention may also include, in addition to the
components (A1) to (C1), component (D1): a polymer which is compatible
with an epoxy resin composition containing the components (A1) to (C1),
and has a characteristic of forming a phase separation structure when the
epoxy resin composition containing the component (D1) is cured, and
various additives as described above.

[0142] Such an epoxy resin composition may be prepared according to a
known method, and may be prepared according to, for example, the methods
described in JP 2012-25892, WO 2011/037239, and the like.

[0143] The viscosity at 30° C. of the epoxy resin composition
according to the first embodiment of the present invention is preferably
300 Pas or less, and more preferably 150 Pas or less. If the viscosity
exceeds 300 Pas, since the epoxy resin composition becomes highly
viscous, handling or impregnation into a reinforcing fiber bundle may
become difficult, and when a tow prepreg is produced therefrom, there may
be problems in reelability from a bobbin, processability, and drape
properties.

[0144] Furthermore, the lower limit of the viscosity is usually about 0.1
Pas, from the reasons that when a tow prepreg passes through a process or
at the time of FW molding, there may be a problem that the epoxy resin
composition supplied to the reinforcing fiber bundle may fall off, or
when a tow prepreg or a reinforcing fiber bundle supplied with a resin is
wound around a mandrel or a liner by FW molding, there may be a problem
that the epoxy resin composition droops and falls down to the liner or a
composite material-reinforced pressure vessel.

[0145] That is, the viscosity at 30° C. of the epoxy resin
composition according to the first embodiment of the present invention is
preferably from 0.1 Pas to 300 Pas, and more preferably from 0.1 Pas to
150 Pas.

[0146] Meanwhile, regarding the range of the viscosity at 30° C. of
the epoxy resin composition according to the first embodiment of the
present invention, it is desirable if the viscosity when the object of
measurement is brought to 30° C. is in the range described above,
and even for an epoxy resin composition exhibiting a viscosity out of the
above-described range under measurement conditions other than 30°
C., if the epoxy resin has a viscosity at 30° C. in the
above-described range, the epoxy resin composition is included in the
scope of the present invention.

[0147] In order to adjust the viscosity of the composition to the range
described above, it is preferable to incorporate the components (A1) to
(C1) respectively at the proportions described above.

[0148] The viscosity of the epoxy resin composition can be measured by the
following method.

[0149] <Method for Measuring Viscosity of Epoxy Resin Composition>

[0150] The viscosity of the resin composition upon temperature increase is
measured under the following measurement conditions, and the viscosity at
30° C. is determined.

[0151] Measurement Conditions

[0152] Apparatus: AR-G2 (manufactured by TA Instruments, Inc.)

[0153] Plate used: 35 mmφ parallel plate

[0154] Plate gap: 0.5 mm

[0155] Measurement frequency: 10 rad/sec

[0156] Rate of temperature increase: 2° C./min

[0157] Stress: 3000 dynes/cm2

Second Embodiment

[0158] The epoxy resin composition according to a second embodiment of the
present invention is an epoxy resin composition including components
(A2), (B2) and (D2) described below, the epoxy resin composition
including 12 to 110 parts by mass of the component (B2) and 1 to 50 parts
by mass of the component (D2) relative to 100 parts by mass of the
component (A2):

[0159] component (A2): an epoxy resin;

[0160] component (B2): a boron trihalide-amine complex; and

[0161] component (D2): a polymer which is compatible with an epoxy resin
composition containing the components (A2) and (B2), and is capable of
forming a phase separation structure after being cured.

[0162] Hereinafter, the various components will be explained.

[0163] The component (A2) according to the second embodiment of the
present invention is an epoxy resin, and the same epoxy resins as those
listed as the component (A1) according to the first embodiment may be
used.

[0164] The component (A2) is preferably at least one component selected
from the group consisting of an epoxy resin having an aromatic ring in
the molecule, and hexahydrophthalic acid diglycidyl ester.

[0165] The component (B2) according to the second embodiment of the
present invention is a boron trihalide-amine complex, and the same boron
trihalide-amine complexes as those listed as the component (B1) according
to the first embodiment may be used.

[0166] Examples of the component (B2) include a boron trichloride-amine
complex and a boron trifluoride-amine complex, and a boron
trichloride-amine complex is preferred.

[0167] The component (D2) according to the second embodiment of the
present invention is a polymer which is compatible with an epoxy resin
composition containing the components (A2) and (B2), and has a
characteristic of forming a phase separation structure in a cured product
obtainable when an epoxy resin containing the component (D2) is cured.

[0168] Examples of the component (D2) include the same polymers as those
listed as the component (D1) according to the first embodiment.

[0169] The component (D2) is preferably at least one component selected
from the group consisting of triblock copolymers and polyamide
elastomers.

[0170] A preferred amount of incorporation of the component (B2) is
preferably from 8 parts by mass to 20 parts by mass, more preferably from
8 parts by mass to 18 parts by mass, even more preferably from 9 parts by
mass to 18 parts by mass, and particularly preferably from 9 parts by
mass to 17 parts by mass, relative to 100 parts by mass of the component
(A2).

[0171] A preferred amount of incorporation of the component (D2) is
preferably 1 to 50 parts by mass, and more preferably 5 to 25 parts by
weight, relative to 100 parts by mass of the component (A2).

[0172] The epoxy resin composition according to the second embodiment of
the present invention may further include additives, to the extent that
the effect of the present invention is not impaired. Regarding the
additives, the same additives as those listed as the additives according
to the first embodiment may be used.

[0173] The content of the additives is preferably 20 parts by weight or
less relative to 100 parts by weight of the epoxy resin composition
according to the second embodiment of the present invention.

[0174] The viscosity at 30° C. of the epoxy resin composition
according to the second embodiment of the present invention is preferably
from 0.1 Pas to 300 Pas, and more preferably from 0.1 Pas to 150 Pas.

Third Embodiment

[0175] The epoxy resin composition according to the third embodiment of
the present invention is an epoxy resin composition including an epoxy
resin, an epoxy resin curing agent, and a thermoplastic resin, and the
epoxy resin composition is an epoxy resin composition having a
characteristic by which, when the composition is cured, a phase of a
cured product of the epoxy resin and a phase of the thermoplastic resin
form a sea-island phase separation structure (that is, phase separation
structure 1), and a sea-island phase separation structure (phase
separation structure 2) is further formed by taking the island structure
in the phase separation structure 1 as a sea structure.

[0176] Meanwhile, the "sea-island phase separation structure" according to
the present specification and the claims is a kind of phase separation
structure. For example, when two kinds of resins are mixed and cured, if
there is a deviation in the mixing ratio, a structure in which the
component in a larger amount constitutes a continuous phase, and the
component in a smaller amount constitutes an isolated phase, is achieved.
At this time, the continuous phase is referred to as "sea structure", and
the isolated phase is referred to as "island structure".

[0177] In regard to the epoxy resin composition according to the third
embodiment of the present invention, when the epoxy resin composition is
cured, the cured product may have high toughness and heat resistance by
forming a special phase separation structure as such. Therefore, the
epoxy resin composition according to the third embodiment of the present
invention can be suitably used as a matrix resin for a reinforcing fiber
composite material, similarly to the epoxy resin compositions according
to the first and second embodiments described above.

[0178] In regard to the phase separation structure 1, it is preferable
that the sea structure is a phase of a cured product of the epoxy resin,
and the island structure is a phase of the thermoplastic resin.
Furthermore, in regard to the phase separation structure 2, the island
structure is preferably a phase of a cured product of the epoxy resin,
and is particularly preferably in a spherical form.

[0179] It is speculated that when the sea structure and the island
structure are respectively formed by these phases, the cured product may
have high toughness and heat resistance. Meanwhile, the "phase of a cured
product of the epoxy resin" may contain components other than the
components derived from the epoxy resin and the epoxy resin curing agent
to the extent that the phase is not destroyed, and the "phase of the
thermoplastic resin" may also similarly contain components other than the
thermoplastic resin to the extent that the phase is not destroyed.

[0180] The length of the major axis of the island structure in the phase
separation structure 1 is not particularly limited, but the length is
preferably 50 nm to 300 μm, more preferably 50 nm to 200 μm, and
even more preferably 50 nm to 100 μm.

[0181] When the length of the major axis is in this range, there is an
advantage that cracks in the cured product of the epoxy resin composition
can easily propagate to the island phase, the crack propagation distance
is elongated, and the toughness value of the cured product is increased.
Furthermore, the length of the major axis of the island structure
(provided that in the case where the island structure is in a spherical
form, the diameter) in the phase separation structure 2 is not
particularly limited as long as the length of the major axis is not
larger than the size of the island structure of the phase separation
structure 1 (that is, the sea structure of the phase separation structure
2). However, the length is preferably 10 nm to 100 μm, more preferably
10 nm to 50 μm, and even more preferably 10 nm to 30 μm.

[0182] When the length of the major axis is in this range, there is an
advantage that cracks in a cured product of the epoxy resin composition
can easily propagate to the island phase, the crack propagation distance
is elongated more in the small island than in the larger island phase,
and the toughness value of the cured product is increased.

[0183] There are no particular limitations on the curing conditions for
the resin composition for forming such a particular sea-island structure;
however, for example, when the rate of temperature increase is adjusted
to 1° C./min or less, and the curing temperature is adjusted to
about 110° C. to 135° C., the curing rate of the
composition becomes appropriate, and a desired phase separation structure
can be easily obtained.

[0184] Meanwhile, the "length of the major axis" as used herein means the
length of the longest part of the island structure.

[0185] In order to measure the length of the major axis, as described in
the Examples of the present application, first, a cured plate was
produced using an epoxy resin composition, a cross-section thereof was
observed with a laser scan microscope, the shortest distances at various
short edges of the island structure were connected, and the length of
connecting their centers with a line was designated as the major axis. A
measurement example of the length of the major axis of an island
structure is illustrated in FIG. 4.

[0186] It is preferable for the epoxy resin composition according to the
third embodiment of the present invention to contain 8 to 20 parts by
weight of the epoxy resin curing agent and 1 to 50 parts by weight of the
thermoplastic resin relative to 100 parts by mass of the epoxy resin.

[0187] Particularly, it is preferable that the various components included
in the composition are substances in the kinds and amounts described
below.

[0188] Hereinafter, the various components will be explained in sequence.

[0189] Regarding the epoxy resin (hereinafter, may be referred to as
component (A3)) that is included in the epoxy resin composition according
to the third embodiment of the present invention, the same epoxy resins
as those listed as the component (A1) according to the first embodiment
may be used. For the component (A3), at least one component selected from
an epoxy resin having an aromatic ring in the molecule and
hexahydrophthalic acid diglycidyl ester is preferred.

[0190] Regarding the epoxy resin curing agent (hereinafter, may be
referred to as component (B3)) that is included in the epoxy resin
composition according to the third embodiment of the present invention,
the same boron trihalide-amine complexes as those listed as the component
(B1) according to the first embodiment may be used. Examples of the
component (B3) include a boron trichloride-amine complex and a boron
trifluoride-amine complex, and a boron trichloride-amine complex is
preferred.

[0191] A preferred amount of incorporation of the component (B3) is
preferably from 8 parts by mass to 20 parts by mass, more preferably from
8 parts by mass to 18 parts by mass, even more preferably from 9 parts by
mass to 18 parts by mass, and particularly preferably from 9 parts by
mass to 17 parts by mass, relative to 100 parts by mass of the component
(A3).

[0192] The thermoplastic resin that is included in the epoxy resin
composition according to the third embodiment of the present invention,
may be component (D3): a polymer which is compatible with an epoxy resin
composition containing the components (A3) and (B3), and has a
characteristic of forming, when an epoxy resin containing the component
(D3) is cured, a phase separation structure in the cured product.

[0193] Specifically, the component (D3) is preferably at last one block
copolymer selected from the group consisting a S-B-M triblock copolymer
and a M-B-M triblock copolymer.

[0194] Here, the various blocks represented by S, B and M are linked by
covalent bonding.

[0195] The block M is a homopolymer of polymethyl methacrylate, or a
copolymer containing methyl methacrylate at a proportion of at least 50%
by mass in terms of monomer relative to the total mass of all the
monomers, which is the feed amount of the block M.

[0196] The block B is a block which is non-compatible with the block M and
has a glass transition temperature of 20° C. or lower. The block M
is a polymer obtained by polymerizing at least one monomer selected from
butadiene, isoprene, 2,3-dimethyl-1,3-butadiene, 1,3-pentadiene,
2-phenyl-1,3-butadiene, and (meth)acrylic acid esters.

[0197] The block S is a block which is non-compatible with the blocks B
and M and has a glass transition temperature higher than the glass
transition temperature of the block B. The block S is a polymer obtained
by polymerizing at least one monomer selected from styrene,
α-methylstyrene and vinyltoluene.

[0198] A specific example of the triblock copolymer M-B-M may be a
copolymer composed of methyl methacrylate-butyl acrylate-methyl
methacrylate, and specific examples thereof include NANOSTRENGTH M22
(manufactured by Arkema S.A.) and NANOSTRENGTH M22N (manufactured by
Arkema S.A.) having polar functional groups.

[0200] Regarding the component (D3), various polymers may be used singly,
or two or more kinds of polymers may be used in combination.

[0201] A preferred amount of incorporation of the component (D3) is
usually 1 to 50 parts by mass, and more preferably 5 to 25 parts by
weight, relative to 100 parts by mass of the component (A3) included in
the third epoxy resin composition of the present invention.

[0202] The epoxy resin composition according to the third embodiment of
the present invention may further include component (C3): rubber
particles.

[0203] Regarding the component (C3), the same rubber particles as those
listed as the component (C1) according to the first embodiment may be
used.

[0204] A preferred amount of incorporation of the component (C3) is
preferably from 12 parts by mass to 110 parts by mass, more preferably
from 16 parts by mass to 100 parts by mass, and particularly preferably
from 20 parts by mass to 80 parts by mass, relative to 100 parts by mass
of the component (A3).

[0205] The epoxy resin composition according to the third embodiment of
the present invention may further include additives to the extent that
the effect of the present invention is not impaired. Regarding the
additives, the same additives as the additives listed in the first
embodiment may be used.

[0206] The content of the additives is preferably 20 parts by weight or
less relative to 100 parts by weight of the epoxy resin composition
according to the third embodiment of the present invention.

[0207] <Tow Prepreg>

[0208] A tow prepreg is an intermediate base material having a fine width
that is obtainable by impregnating a reinforcing fiber bundle in which
several thousand to several ten thousand strands of filaments are
unidirectionally arranged, with a resin composition. The tow prepreg of
the present invention is obtained by impregnating a reinforcing fiber
bundle with the epoxy resin composition of the present invention
described above. There are no particular limitations on the fiber
diameter and number of strands of the filament that constitutes this
reinforcing fiber bundle, but the fiber diameter is preferably 3 to 100
μm, and the number of strands is preferably 1,000 to 70,000. Also, the
"fiber diameter" according to the present invention is an equivalent
diameter of a circle having an area equal to that of a cross-section of
each fiber.

[0209] If the fiber diameter is less than 3 μm, for example, when the
filaments make transverse movements on the surface of a roll, a bobbin or
the like during various processing processes, the filaments may be
broken, or fluff may be generated. If the fiber diameter is more than 100
μm, the filaments are hardened, and bendability tends to decrease.

[0210] Regarding the reinforcing fiber bundle according to the present
invention, strengthening fibers that are used in conventional
fiber-reinforced composite materials, such as glass fiber, carbon fiber,
aramid fiber, graphite fiber and boron fiber, can be used. Among others,
preferred is a carbon fiber or graphite fiber having a strand strength
according to JIS R7601 of 3500 MPa or more; more preferred is a carbon
fiber or graphite fiber having a strand strength of 4500 MPa or more; and
even more preferred is a carbon fiber having a strand strength of 5000
MPa or more. Higher strand strength is more preferable.

[0211] Meanwhile, when the reinforcing fiber bundle is a carbon fiber
bundle, the fiber diameter of the filament is preferably 3 to 12 μm,
and the number of strands is preferably 1,000 to 70,000.

[0212] If the fiber diameter is less than 3 μm, for example, when the
filaments make transverse movements on the surface of a roll, a bobbin or
the like during various processing processes, the filaments may be
broken, or fluff may be generated. The upper limit is usually about 12
μm from the viewpoint of the difficulties in the production of carbon
fiber.

[0213] <Content of Epoxy Resin Composition>

[0214] The content of the epoxy resin composition that is included in the
tow prepreg is preferably from 20% by weight to 40% by weight. When the
content is 20% by weight or more, the epoxy resin composition can be
sufficiently made to easily spread through the reinforcing fiber bundle.
When the content is 40% by weight or less, since the fiber content by
volume in the reinforcing fiber composite material is high, mechanical
characteristics can be manifested effectively. In order to manifest the
performance of mechanical characteristics more effectively, the content
is more preferably from 20% by weight to 30% by weight.

[0215] <Method for Curing Epoxy Resin Composition>

[0216] The epoxy resin composition of the present invention can be cured
by a known means. Among others, it is preferable to use a heating means
which is capable of uniformly heating the surroundings of the epoxy resin
composition, such as an air heating furnace. Preferred curing temperature
and curing time may vary depending on the kinds of the component (A) and
component (B); however, the epoxy resin composition can be usually cured
by heating at about 110° C. to 135° C. for about 2 hours.

[0217] The tow prepreg of the present invention can be produced by any
known production method. Among others, it is preferable to produce the
tow prepreg by the following procedure.

[0218] <Preferred Method for Producing Tow Prepreg>

[0219] (1) Before an epoxy resin composition is supplied to at least one
surface of a reinforcing fiber bundle, a tow is heated and spread out in
advance.

[0220] (2) An epoxy resin composition is supplied to at least one surface
of the reinforcing fiber bundle.

[0222] (4) The temperature of the tow prepreg is cooled to about room
temperature.

[0223] (5) The tow prepreg is wound around a paper tube or the like.

[0224] It is desirable that the reinforcing fiber bundle is spread out to
have a flat shape, since the contact area with the epoxy resin
composition is enlarged. Examples of the method for spreading out include
a method of scraping with a cylindrical bar, a method of applying
vibration, and a method of squashing. Furthermore, when the reinforcing
fiber bundle is spread out, the reinforcing fiber bundle is heated first
in order to soften the sizing agent applied on the reinforcing fiber
bundle and to make it easier for the bundle to spread out. It is
preferable to heat the reinforcing fiber bundle up to about the softening
point of the sizing agent applied thereon. Moreover, preheating of the
tow is also meaningful for raising the temperature of the reinforcing
fiber bundle in advance so that the resin temperature does not decrease
at the time of the penetration of the resin into the reinforcing fiber
bundle. When the temperature of the reinforcing fiber bundle is increased
by heating to a temperature higher than or equal to the resin temperature
before contact, there is no chance that the temperature of the
reinforcing fiber bundle after the contact between the reinforcing fiber
bundle and the resin becomes lower than the resin temperature before
contact. Regarding the heating method, heating by contacting with a
heating element; and non-contact heating methods such as electric
heating, dielectric heating, infrared heating, and atmosphere heating,
can all be used.

[0225] According to the present invention, spreading of the reinforcing
fiber bundle may be carried out in-line, or may be carried out off-line.
For example, a commercially available tape-shaped reinforcing fiber
bundle that has been spread out is regarded as a reinforcing fiber bundle
that has been spread out off-line.

[0226] Examples of the method for supplying the epoxy resin composition
include a resin bath method; a rotating roll method; a on-paper transfer
method; the nozzle dropping method described in JP 09-176346 A, JP
2005-335296 A, and JP 2006-063173 A; and the resin contact and tow
transfer method described in JP 08-073630 A, JP 09-031219 A, and JP
8-73630 A.

[0227] Among them, due to the control of the amount of supply of the epoxy
resin composition or the ease of implementation, a rotating roll method
and a resin contact and tow transfer method are preferred as the method
for supplying the epoxy resin composition. Furthermore, the width of the
reinforcing fiber bundle is usually not stabilized, and there are
fluctuations in the way of spreading. Therefore, as described in JP
8-73630 A, it is effective to spread out the reinforcing fiber bundle and
then to stabilize the width by narrowing the tow width immediately before
the resin contact or during the resin contact. A specific example thereof
may be a method of providing grooves having a predetermined width at the
resin discharge port or at a position immediately before that, running
the reinforcing fiber bundle inside the groove, and thereby narrowing the
width of the reinforcing fiber bundle.

[0228] For the method for impregnating the reinforcing fiber bundle with
the epoxy resin composition, any known impregnation method can be used.
Among others, a method of scraping against a heating element such as a
heating roll or a hot plate; a method of allowing a reinforcing fiber
bundle supplied with an epoxy resin composition to pass through a heating
furnace during idle running; and a method of heating with a non-contact
heating means such as air electrothermal heating, electric heating,
dielectric heating, or infrared heating, are preferred. It is more
preferable to have the reinforcing fiber bundle heated with a non-contact
heating means, between the time point where the epoxy resin composition
is supplied to the reinforcing fiber bundle and the time point where the
reinforcing fiber bundle is heated by a heating element, and between a
heating element and a heating element, so as to prevent lowering of the
temperatures of the reinforcing fiber bundle and the epoxy resin
composition.

[0229] Furthermore, in regard to the resin impregnation process, it is
preferable to add a process of moving the filaments that constitute the
reinforcing fiber bundle in a transverse direction (direction
perpendicular to the longitudinal direction) by applying an external
force to the reinforcing fiber bundle, changing the relative positions
between the filaments, and thereby increasing the opportunity of contact
between the resin and the filaments. An effect of uniform impregnation
equal or superior the impregnation effect based on simple pressurization
or the capillary phenomenon can be obtained.

[0230] Specifically, resin impregnation is carried out by at least one
means of folding the reinforcing fiber bundle, spreading out the
reinforcing fiber bundle, shrinking the reinforcing fiber bundle, and
twisting the reinforcing fiber bundle. In regard to these means, the
folding means and the twisting means tend to narrow the width of the
reinforcing fiber, similarly to the width-shrinking means. Also, when a
means having an effect of narrowing the width of the reinforcing fiber
bundle and a means for widening the width of the reinforcing fiber bundle
are used in combination, the effect of uniform impregnation is increased.
Meanwhile, twisting may be carried out at the time of resin impregnation,
and if a state free of twisting is needed after impregnation, untwisting
may be carried out after impregnation. Furthermore, it is false twisting,
it is not necessary to perform untwisting, and this is desirable in a
case in which an untwisted reinforcing fiber bundle is needed.
Furthermore, when scraping is added simultaneously with or immediately
after twisting, the width of the reinforcing fiber bundle tends to be
widened, and due to the transfer in the thickness direction of the resin,
uniformity of impregnation is increased.

[0231] In regard to the uniform impregnation by transverse direction
movement of filaments, scraping the reinforcing fiber bundle by bringing
the reinforcing fiber bundle into contact with a rotating body that
rotates at a circumferential speed of less than the running speed of the
reinforcing fiber bundle, is useful for the deposition of fluff or
cleaning of the roll. If the reinforcing fiber bundle is in a scraped
state, the reinforcing fiber bundle will not be entwined on the surface
of the rotating body, and since the rotating body is rotating while being
rubbed with the reinforcing fiber bundle, the surface contacting with the
reinforcing fiber bundle is always in a state of having been cleaned, and
this is also useful for an enhancement of the production environment.
However, it is preferable to set the circumferential speed of the
rotating body to be from 50% to 99% of the running sped of the
reinforcing fiber bundle. When the circumferential speed of the rotating
body is 1/2 or more of the running speed of the reinforcing fiber bundle,
the reinforcing fiber bundle does not easily undergo fluff generation due
to being strongly scraped, and it is not likely to have a problem when
the reinforcing fiber is wound up in the subsequent processes, or a tow
prepreg that is wound around a paper tube is reeled off.

[0232] When the epoxy resin composition is uniformly impregnated into the
reinforcing fiber bundle, the mechanical characteristics of the
reinforcing fiber composite material thus produced are enhanced, and the
effect of the present invention is sufficiently obtained.

[0233] It is preferable to have the reinforcing fiber bundle that has been
uniformly impregnated with the epoxy resin composition, cooled to about
room temperature until the process of winding around a paper tube, using
a known cooling means such as scraping with a cooling body or a
non-contact cooling means. If the reinforcing fiber bundle is wound in a
state of not being sufficiently cooled, since the epoxy resin composition
has low viscosity, slipping occurs at the time of winding so that the
form of roll is disturbed; or, since a state of elevated temperature is
sustained for a relatively long time at the central area, making the
escape of heat more difficult, there is a possibility that the pot life
of the epoxy resin composition may be shortened.

[0234] The tow prepreg of the present invention obtained in this manner
has advantages (features) of having excellent reelability from a bobbin,
excellent processability and excellent drape properties, and therefore,
the tow prepreg is adequate for filament winding molding, pultrusion
molding and the like.

[0235] <Composite Material-Reinforced Pressure Vessel>

[0236] A "composite material-reinforced pressure vessel" means a pressure
vessel that has been reinforced with a composite material.

[0237] A "composite material" means a fiber-reinforced composite material,
and according to the present invention, the composite material means a
cured product obtainable by heating (and optionally under pressure) and
curing the tow prepreg of the present invention, and then cooling the
resultant; or a cured product obtainable by impregnating a reinforcing
fiber bundle with the epoxy resin composition of the present invention,
subsequently heating (and optionally under pressure) and curing the
impregnated fiber bundle without going through the state of prepreg, and
then cooling the resultant.

[0238] The composite material of the present invention can be used for
general industrial applications such as sports goods, automobiles,
pressure vessels, airplanes and tendons; however, the composite material
is characterized by exhibiting high performance particularly when used in
a pressure vessel or a tendon. Particularly, since satisfactory
performance as a pressure vessel is obtained by reinforcement using a
small amount of the composite material when the composite material is
used as a pressure vessel for hydrogen storage or as a pressure vessel to
be mounted in a movable body such as a vehicle, a more lightweight
pressure vessel can be obtained, and thus, that advantage is most
effectively utilized.

[0239] The composite material-reinforced pressure vessel of the present
invention (hereinafter, may be referred to simply as "pressure vessel of
the present invention") is usually formed such that a liner made of a
resin or a metal is used in the inner layer of the pressure vessel, and
the outer surface of this liner is covered with a composite material
layer.

[0240] <Liner>

[0241] For the liner used in the method for producing the composite
material-reinforced pressure vessel of the present invention, a resin
liner or a metal liner can be selected and used according to the use.

[0242] Meanwhile, the "liner" as used in the present specification and the
claims is composed of a tubular body and panels for closing the openings
at both ends of the body, and usually, one of the panels at both ends is
provided with a metal cap installation area, while the other panel is not
provided with a metal cap installation area.

[0243] In a pressure vessel for hydrogen storage or a pressure vessel to
be mounted in a moving body such as a vehicle, it is preferable to use a
resin liner so that the weight of the pressure vessel can be further
reduced. Regarding the resin liner, a liner produced by shaping a
thermoplastic resin such as high density polyethylene into a vessel shape
by rotary molding or blow molding, and attaching a metal cap thereto, can
be used. Since a resin liner has relatively low heat resistance, it is
required to suppress the reaction heat generation at the time of curing
the epoxy resin composition, to a low level. The present invention
includes relatively large amounts of components that do not induce a heat
generating reaction, such as rubber particles, other than the epoxy resin
or the curing agent; therefore, heat generation at the time of curing
occurs at a low level, and the present invention can be suitably used
even if the liner is made of a resin. Also, a metal liner may be obtained
by shaping an aluminum alloy, stainless steel or the like, which is in a
pipe shape or a plate shape, into a vessel shape by spinning processing
or the like, and then providing a cap shape thereto.

[0244] <Filament Winding (FW) Molding>

[0245] In regard to the process for forming a composite material layer in
the pressure vessel of the present invention, there is available a
filament winding (FW) method as a representative method for winding the
tow prepreg or a reinforcing fiber bundle that has impregnated with an
epoxy resin composition, around a liner.

[0246] The filament winding (FW) method is a molding method including
paralleling one or plural reinforcing fiber bundles, and continuously
winding the reinforcing fiber bundles around a rotating tank liner at a
desired tension and at a desired angle, while supplying a matrix resin to
impregnate the reinforcing fiber bundles with the matrix resin; or, in
the case of using a tow prepreg, paralleling one or plural reinforcing
fiber bundles, and continuously winding the reinforcing fiber bundles
around a rotating tank liner at a desired tension and at a desired angle,
without performing supply and impregnation of a matrix resin.

[0247] The filament winding apparatus (FW machine) used in the present
invention may be any conventionally known FW machine, and this may a FW
machine capable of winding only one reinforcing fiber bundle or tow
prepreg around a mandrel or a liner fixed to a mandrel, or may be a FW
machine capable of winding plural reinforcing fiber bundles or tow
prepregs simultaneously.

[0248] In the case of supplying an epoxy resin composition to a
reinforcing fiber bundle and impregnating the reinforcing fiber bundle
during FW molding, a method of supplying the epoxy resin composition by
applying the epoxy resin composition to a certain thickness on a
cylindrical drum using a doctor blade or the like and then bringing the
fibers into contact thereon, and impregnating the epoxy resin composition
into the interior of the reinforcing fiber bundle using a roller or the
like; a method of immersing the fibers in a bath of the epoxy resin
composition, and then scraping off any unnecessary epoxy resin
composition using a bar, a guide or the like; a method of quantitatively
transporting the epoxy resin composition using a means such as a
dispenser, and thereby applying the epoxy resin composition; and the like
may be used, without any particular limitations. Regarding a method of
applying the epoxy resin composition by accurately managing the target
amount without supplying excess resin to the reinforcing fiber bundle, a
method of using a drum or a dispenser is preferred.

[0249] The composite material-reinforced pressure vessel of the present
invention is a composite material-reinforced pressure vessel produced by
a production method including a step of paralleling one or plural
reinforcing fiber bundles, and winding the reinforcing fiber bundles
around a rotating tank liner at a desired tension and at a desired angle,
while supplying a matrix resin and impregnating the reinforcing fiber
bundles with the matrix resin; or in the case of using a tow prepreg, a
step of paralleling one or plural reinforcing fiber bundles, and winding
the reinforcing fiber bundles around a rotating tank liner at a desired
tension and at a desired angle without performing supply and impregnation
of a matrix resin, and a step of heating (and optionally under pressure)
the reinforcing fiber bundles or tow prepreg wound around the tank liner
to cure.

[0250] In the production of the composite material-reinforced pressure
vessel of the present invention, a composite material intermediate that
is formed around the outer circumference of the liner forms a layered
structure in order to best utilize the features of the composite material
intermediate as an anisotropic material.

[0251] According to the present invention, the configuration of the
layered structure, thicknesses of various layers, and the angle and
tension for winding the reinforcing fiber bundle or tow prepreg around a
liner, can be freely selected in accordance with the use or shape of the
vessel, the kind of the content, and the like.

[0252] Since the composite material-reinforced pressure vessel of the
present invention can give satisfactory performance as a pressure vessel
by reinforcement using a small amount of a composite material, the
composite material-reinforced pressure vessel is lightweight and is
suitably used particularly as a pressure vessel for hydrogen storage or a
pressure vessel to be mounted in a moving body such as a vehicle.

[0253] <Other Applications>

[0254] Since a composite material produced from the epoxy resin
composition of the present invention or from a tow prepreg using this
epoxy resin composition, exhibits excellent tensile strength, the
composite material is also suitable for the use as a tendon, in addition
to the use as a pressure vessel described above.

[0255] According to an embodiment of the present invention, there is
provided

[0256] an epoxy resin composition,

[0257] the epoxy resin composition including components (A1) to (C1)
described below,

[0258] wherein the content of the component (B1) is 8 to 20 parts by mass
relative to 100 parts by mass of the component (A1), and

[0259] the content of the component (C1) is 12 to 110 parts by mass
relative to 100 parts by mass of the component (A1):

[0260] component (A1): at least one epoxy resin selected from the group
consisting of an epoxy resin having an aromatic ring in the molecule and
an epoxy resin having an aliphatic ring in the molecule;

[0261] component (B1): at least one selected from the group consisting of
a boron trifluoride-amine complex and a boron trichloride-amine complex;
and

[0262] component (C1): at least one kind of rubber particles selected from
the group consisting of crosslinked rubber particles, and core-shell type
rubber particles obtained by graft-polymerizing, on the surface of
crosslinked rubber particles, a polymer different from the polymer that
constitutes the crosslinked rubber particles.

[0263] According to another embodiment of the present invention, there is
provided

[0264] an epoxy resin composition,

[0265] the epoxy resin composition including components (A1) to (C1)
described below,

[0266] wherein the content of the component (B1) is 8 to 20 parts by mass
relative to 100 parts by mass of the component (A1), and

[0267] the content of the component (C1) is 12 to 110 parts by mass
relative to 100 parts by mass of the component (A1):

[0268] component (A1): at least one component selected from the group
consisting of an epoxy resin having a bifunctional aromatic ring in the
molecule, an epoxy resin having a trifunctional aromatic ring in the
molecule, an epoxy resin having a tetrafunctional aromatic ring in the
molecule, a compound in which an aliphatic ring is condensed with an
epoxy ring, and a compound in which a substituent containing an epoxy
group, such as a glycidyl group, is bonded to an aliphatic ring;

[0269] component (B1): at least one component selected from the group
consisting of a boron trifluoride-aniline complex, a boron
trifluoride-p-chloroaniline complex, a boron trifluoride-ethylamine
complex, a boron trifluoride-isopropylamine complex, a boron
trifluoride-benzylamine complex, a boron trifluoride-dimethylamine
complex, a boron trifluoride-diethylamine complex, a boron
trifluoride-dibutylamine complex, a boron trifluoride-piperidine complex,
a boron trifluoride-dibenzylamine complex, compounds in which fluorine
atoms in the above-mentioned amine complexes are replaced with chlorine
atoms, and a boron trichloride-dimethyloctylamine complex component; and

[0271] the core-shell type rubber articles are such that the core
component is a polymer obtained by polymerizing at least one monomer
selected from the group consisting of a vinyl monomer, a conjugated
diene-based monomer, an acrylic acid ester-based monomer, and a
methacrylic acid ester-based monomer, or a silicone resin; and the shell
component is a polymer obtained by polymerizing at least one monomer
selected from the group consisting of an acrylic acid ester-based
monomer, a methacrylic acid ester-based monomer, and an aromatic vinyl
monomer.

[0272] According to another embodiment of the present invention, there is
provided

[0273] an epoxy resin composition,

[0274] the epoxy resin composition including components (A1) to (C1)
described below,

[0275] wherein the content of the component (B1) is 8 to 20 parts by mass
relative to 100 parts by mass of the component (A1), and

[0276] the content of the component (C1) is 12 to 110 parts by mass
relative to 100 parts by mass of the component (A1):

[0278] component (B1): at least one component selected from the group
consisting of a boron trifluoride-piperidine complex and a boron
trichloride-dimethyloctylamine compound; and

[0279] component (C1): at least one component selected from the group
consisting of butadiene rubber, and core-shell type rubber particles in
which the core component is a crosslinked rubber-like polymer composed of
styrene and butadiene, and the shell component is a copolymer of methyl
methacrylate and styrene.

[0280] According to another embodiment of the present invention, there is
provided

[0281] an epoxy resin composition,

[0282] the epoxy resin composition including components (A1) to (C1)
described below,

[0283] wherein the content of the component (B1) is 8 to 20 parts by mass
relative to 100 parts by mass of the component (A1), and

[0284] the content of the component (C1) is 12 to 110 parts by mass
relative to 100 parts by mass of the component (A1):

[0285] component (A1): at least one component selected from the group
consisting of a bisphenol A diglycidyl ether type epoxy resin, a
bisphenol F diglycidyl ether type epoxy resin, a
N,N,N',N'-tetraglycidyldiaminodiphenylmethane, and hexahydrophthalic acid
diglycidyl ester;

[0286] component (B1): at least one component selected from the group
consisting of a boron trifluoride-piperidine complex and a boron
trichloride-dimethyloctylamine complex; and

[0287] component (C1): at least one component selected from the group
consisting of butadiene rubber, and core-shell type rubber particles in
which the core component is a crosslinked rubber-like polymer composed of
styrene and butadiene, and the shell component is a copolymer of methyl
methacrylate and styrene.

[0288] According to another embodiment of the present invention, there is
provided

[0289] an epoxy resin composition,

[0290] the epoxy resin composition including components (A1) to (C1)
described below,

[0291] wherein the content of the component (B1) is 8 to 20 parts by mass
relative to 100 parts by mass of the component (A1), and

[0292] the content of the component (C1) is 12 to 110 parts by mass
relative to 100 parts by mass of the component (A1):

[0293] component (A1): at least one component selected from the group
consisting of an epoxy resin having an aromatic ring in the molecule and
a compound in which a substituent containing an epoxy group is bonded to
an aliphatic ring;

[0295] component (C1): at least one kind of rubber particles selected from
the group consisting of crosslinked rubber particles, and core-shell type
rubber particles in which, on the surface of crosslinked rubber
particles, a polymer different from the polymer that constitutes the
crosslinked rubber particles is graft-polymerized.

[0296] According to another embodiment of the present invention, there is
provided

[0297] an epoxy resin composition,

[0298] the epoxy resin composition including components (A1) to (C1)
described below,

[0299] wherein the content of the component (B1) is 8 to 20 parts by mass
relative to 100 parts by mass of the component (A1),

[0300] the content of the component (C1) is 12 to 110 parts by mass
relative to 100 parts by mass of the component (A1), and

[0301] the content of the component (D1) is 1 to 50 parts by mass relative
to 100 parts by mass of the component (A1):

[0302] component (A1): at least one epoxy resin component selected from
the group consisting of an epoxy resin having an aromatic ring in the
molecule, and an epoxy resin having an aliphatic ring in the molecule;

[0303] component (B1): at least one component selected from the group
consisting of a boron trichloride-amine complex and a boron
trichloride-amine complex;

[0304] component (C1): at least one kind of rubber particles selected from
the group consisting of crosslinked rubber particles, and core-shell type
rubber particles in which, on the surface of crosslinked rubber
particles, a polymer different from the polymer that constitutes the
crosslinked rubber particles is graft-polymerized; and

[0305] component (D1): a polymer which is compatible with an epoxy resin
composition containing the components (A1) to (C1), and has a
characteristic of forming a phase separation structure when an epoxy
resin composition containing the component (D1) is cured.

[0306] According to another embodiment of the present invention, there is
provided

[0307] an epoxy resin composition,

[0308] the epoxy resin composition including components (A1) to (C1)
described below,

[0309] wherein the content of the component (B1) is 8 to 20 parts by mass
relative to 100 parts by mass of the component (A1),

[0310] the content of the component (C1) is 12 to 110 parts by mass
relative to 100 parts by mass of the component (A1), and

[0311] the content of the component (D1) is 1 to 50 parts by mass relative
to 100 parts by mass of the component (A1):

[0312] component (A1): at least one component selected from the group
consisting of a bisphenol A diglycidyl ether type epoxy resin, a
bisphenol F diglycidyl ether type epoxy resin, a
N,N,N',N'-tetraglycidyldiaminodiphenylmethane, and hexahydrophthalic acid
diglycidyl ester;

[0313] component (B1): at least one component selected from the group
consisting of a boron trifluoride-piperidine complex and a boron
trichloride-dimethyloctylamine complex;

[0314] component (C1): at least one component selected from the group
consisting of butadiene rubber, and core-shell type rubber particles in
which the core component is a crosslinked rubber-like polymer composed of
styrene and butadiene, and the shell component is a copolymer of methyl
methacrylate and styrene; and

[0315] component (D1): at least one component selected from the group
consisting of triblock copolymers and polyamide elastomers.

[0316] According to another embodiment of the present invention, there is
provided

[0317] an epoxy resin composition,

[0318] the epoxy resin composition including components (A2), (B2) and
(D2) described below,

[0319] wherein the content of the component (B2) is 8 to 20 parts by mass
relative to 100 parts by mass of the component (A2),

[0320] the content of the component (D2) is 1 to 50 parts by mass relative
to 100 parts by mass of the component (A2):

[0321] component (A2): at least one epoxy resin selected from the group
consisting of an epoxy resin having an aromatic ring in the molecule and
an epoxy resin having an aliphatic ring in the molecule;

[0322] component (B1): at least one component selected from the group
consisting of a boron trichloride-amine complex and a boron
trichloride-amine complex; and

[0323] component (D2): a polymer which is compatible with an epoxy resin
composition containing the components (A2) and (B2) and is capable of
forming a phase separation structure in a cured product when an epoxy
resin containing the component (D2) is cured.

[0324] According to another embodiment of the present invention, there is
provided

[0325] an epoxy resin composition,

[0326] the epoxy resin composition including components (A2), (B2) and
(D2) described below,

[0327] wherein the content of the component (B2) is 8 to 20 parts by mass
relative to 100 parts by mass of the component (A2); and

[0328] the content of the component (D2) is 1 to 50 parts by mass relative
to 100 parts by mass of the component (A2):

[0329] component (A2): at least one component selected from the group
consisting of an epoxy resin having a bifunctional aromatic ring in the
molecule, an epoxy resin having a trifunctional aromatic ring in the
molecule, an epoxy resin having a tetrafunctional aromatic ring in the
molecule, a compound in which an aliphatic ring is condensed with an
epoxy resin, and a compound in which a substituent containing an epoxy
group, such as a glycidyl group, is bonded to an aliphatic ring;

[0330] component (B2): at least one component selected from the group
consisting of a boron trifluoride-aniline complex, a boron
trifluoride-p-chloroaniline complex, a boron trifluoride-ethylamine
complex, a boron trifluoride-isopropylamine complex, a boron
trifluoride-benzylamine complex, a boron trifluoride-dimethylamine
complex, a boron trifluoride-diethylamine complex, a boron
trifluoride-dibutylamine complex, a boron trifluoride-piperidine complex,
a boron trifluoride-dibenzylamine complex, compounds in which fluorine
atoms in the above-mentioned amine complexes are replaced with chlorine
atoms, and a boron trichloride-dimethyloctylamine complex component; and

[0331] component (D2): triblock copolymers and polyamide elastomers.

[0332] According to another embodiment of the present invention, there is
provided

[0333] an epoxy resin composition,

[0334] the epoxy resin composition including components (A2), (B2) and
(D2) described below,

[0335] wherein the content of the component (B2) is 8 to 20 parts by mass
relative to 100 parts by mass of the component (A2); and

[0336] the content of the component (D2) is 1 to 50 parts by mass relative
to 100 parts by mass of the component (A2):

[0338] component (B2): at least one component selected from the group
consisting of a boron trifluoride-aniline complex, a boron
trifluoride-p-chloroaniline complex, a boron trifluoride-ethylamine
complex, a boron trifluoride-isopropylamine complex, a boron
trifluoride-benzylamine complex, a boron trifluoride-dimethylamine
complex, a boron trifluoride-dibenzylamine complex, compounds in which
fluorine atoms in the above-mentioned amine complexes are replaced with
chlorine atoms, and a boron trichloride-dimethyloctylamine complex
component; and

[0339] component (D2): at least one component selected from the group
consisting of a M-B-M-triblock copolymer, a S-B-M triblock copolymer, and
a polyamide elastomer,

[0340] provided that the block M is a homopolymer of polymethyl
methacrylate, or a copolymer containing methyl methacrylate at a
proportion of at least 50% by mass in terms of monomer relative to the
total mass of all the monomers, which is the feed amount of the block M;

[0341] the block B is a polymer obtained by polymerizing one or more
monomers selected from butadiene, isoprene, 2,3-dimethyl-1,3-butadiene,
1,3-pentadiene, 2-phenyl-1,3-butadiene and (meth)acrylic acid esters as
monomers; and

[0342] the block S is a polymer obtained by polymerizing one or more
monomers selected from styrene, α-methylstyrene and vinyltoluene as
monomers.

[0343] According to another embodiment of the present invention, there is
provided

[0344] an epoxy resin composition,

[0345] the epoxy resin composition including an epoxy resin, an epoxy
resin curing agent which is a boron trihalide-amine complex, and a
thermoplastic resin,

[0346] wherein the epoxy resin is at least one epoxy resin selected from
the group consisting of an epoxy resin having an aromatic ring in the
molecule and an epoxy resin having an aliphatic ring in the molecule,

[0347] the epoxy resin curing agent which is a boron trihalide-amine
complex is at least one selected from the group consisting of a boron
trichloride-amine complex and a boron trichloride-amine complex,

[0348] the thermoplastic resin is at least one block copolymer selected
from the group consisting of a S-B-M triblock copolymer and a M-B-M
triblock copolymer,

[0349] the various blocks represented by S, B and M are linked by covalent
bonding,

[0350] the block M is a homopolymer of polymethyl methacrylate, or a
polymer containing methyl methacrylate at a proportion of at least 50% by
mass in terms of monomer relative to the total mass of all the monomers,
which is the feed amount of the block M,

[0351] the block B is a block which is non-compatible with the block M and
has a glass transition temperature of 20° C. or lower,

[0352] the block S is a block which is non-compatible with the blocks B
and M and has a glass transition temperature higher than the glass
transition temperature of the block B,

[0353] the epoxy resin composition having a characteristic of forming,
when the composition is cured, a phase separation structure 1 in which a
phase of a cured product of the epoxy resin composition and a phase of
the thermoplastic resin constitute a sea-island phase separation
structure, and

[0354] further forming a phase separation structure 2 which is a
sea-island phase separation structure, by taking the island structure in
the phase separation structure 1 as a sea structure.

[0355] According to another embodiment of the present invention, there is
provided

[0356] an epoxy resin composition,

[0357] the epoxy resin composition including an epoxy resin, an epoxy
resin curing agent which is a boron trihalide-amine complex, and a
thermoplastic resin,

[0359] the epoxy resin curing agent which is a boron trihalide-amine
complex, is at least one component selected from the group consisting of
a boron trifluoride-aniline complex, a boron trifluoride-p-chloroaniline
complex, a boron trifluoride-ethylamine complex, a boron
trifluoride-isopropylamine complex, a boron trifluoride-benzylamine
complex, a boron trifluoride-dimethylamine complex, a boron
trifluoride-dibenzylamine complex, compounds in which fluorine atoms in
the above-mentioned amine complexes are replaced with chlorine atoms, and
a boron trichloride-dimethyloctylamine complex component;

[0360] the thermoplastic resin is at least one block copolymer selected
from the group consisting of a S-B-M triblock copolymer and a M-B-M
triblock copolymer,

[0361] in which the various blocks represented by S, B and M are linked by
covalent bonding;

[0362] the block M is a homopolymer of polymethyl methacrylate, or a
polymer containing methyl methacryl ate at a proportion of at least 50%
by mass in terms of monomer relative to the total mass of all the
monomers, which is the feed amount of the block M;

[0363] the block B is a block which is non-compatible with the block M and
has a glass transition temperature of 20° C. or lower;

[0364] the block S is a block which is non-compatible with the blocks B
and M and has a glass transition temperature higher than the glass
transition temperature of the block B,

[0365] the epoxy resin composition having a characteristic of forming,
when the composition is cured, a phase separation structure 1 in which a
phase of a cured product of the epoxy resin composition and a phase of
the thermoplastic resin constitute a sea-island phase separation
structure, and

[0366] further forming a phase separation structure 2 which is a
sea-island phase separation structure, by taking the island structure in
the phase separation structure 1 as a sea structure.

[0367] According to another embodiment of the present invention, there is
provided

[0368] an epoxy resin composition,

[0369] the epoxy resin composition including an epoxy resin, an epoxy
resin curing agent which is a boron trihalide-amine complex, a
thermoplastic resin, and rubber particles,

[0371] the epoxy resin curing agent which is a boron trihalide-amine
complex, is at least one component selected from the group consisting of
a boron trifluoride-aniline complex, a boron trifluoride-p-chloroaniline
complex, a boron trifluoride-ethylamine complex, a boron
trifluoride-isopropylamine complex, a boron trifluoride-benzylamine
complex, a boron trifluoride-dimethylamine complex, a boron
trifluoride-dibenzylamine complex, compounds in which fluorine atoms in
the above-mentioned amine complexes are replaced with chlorine atoms, and
a boron trichloride-dimethyloctylamine complex component;

[0372] the thermoplastic resin is at least one block copolymer selected
from the group consisting of a S-B-M triblock copolymer and a M-B-M
triblock copolymer,

[0373] in which the various blocks represented by S, B and M are linked by
covalent bonding;

[0374] the block M is a homopolymer of polymethyl methacryl ate, or a
polymer containing methyl methacrylate at a proportion of at least 50% by
mass in terms of monomer relative to the total mass of all the monomers,
which is the feed amount of the block M;

[0375] the block B is a block which is non-compatible with the block M and
has a glass transition temperature of 20° C. or lower;

[0376] the block S is a block which is non-compatible with the blocks B
and M and has a glass transition temperature higher than the glass
transition temperature of the block B,

[0377] the rubber particles are at least one component selected from the
group consisting of butadiene rubber, and core-shell type rubber
particles in which the core component is a crosslinked rubber-like
polymer composed of styrene and butadiene, and the shell component is a
copolymer of methyl methacrylate and styrene,

[0378] the epoxy resin composition having a characteristic of forming,
when the composition is cured, a phase separation structure 1 in which a
phase of a cured product of the epoxy resin composition and a phase of
the thermoplastic resin constitute a sea-island phase separation
structure, and

[0379] further forming a phase separation structure 2 which is a
sea-island phase separation structure, by taking the island structure in
the phase separation structure 1 as a sea structure.

EXAMPLES

[0380] Hereinafter, the present invention will be described in more detail
by way of Examples and Comparative Examples, but the present invention is
not intended to be limited to these.

Examples and Comparative Examples

[0381] The raw materials of the resin compositions used in the various
examples, the preparation method, and the method for measuring various
properties will be described below. The compositions of various epoxy
resin compositions, and the results for the measurement of properties are
summarized in Table 1 for the Examples, and in Table 2 for the
Comparative Examples. Meanwhile, the values for the various components in
Table 1 and Table 2 represent the parts by mass of the various components
incorporated into epoxy resin compositions.

[0382] <Raw Material>

[0383] The following raw materials were used in Examples and Comparative
Examples.

[0515] An epoxy resin composition having the composition described in
Table 1 was prepared.

[0516] CY-184 and M52N were weighed in a flask, and while the flask was
heated in an oil bath at 145° C. to 155° C., the content of
the flask was stirred until the content became uniform. Thereafter, the
flask was removed from the oil bath, the flask was left to cool until the
temperature of the content reached 60° C. or lower, and the
remaining raw materials were weighed and added to the flask.
Subsequently, while the flask was heated in a water bath at 55° C.
to 65° C., the content of the flask was stirred until the content
became uniform, and thus an epoxy resin composition was obtained.

[0517] <Preparation of Resin Composition of Comparative Example 1>

[0518] An epoxy resin composition having the composition described in
Table 1 was prepared.

[0519] The entire amounts of DICY7 and OMICURE 24 were dispersed in a
portion of jER828 using a three-roll. The jER828 having DICY7 and OMICURE
24 dispersed therein, and the remaining portion of jER828 were introduced
into a flask, and while the flask was heated to 40° C. to
50° C., the content of the flask was stirred until the content
became uniform.

[0520] For the epoxy resin compositions obtained in Example 1 and
Comparative Example 1, storage stability and curability were measured by
the following methods, and for the cured resins of the respective
compositions, the glass transition temperature and KIc were measured. The
results are presented in Table 1.

[0521] <Examination of Storage Stability>

[0522] Storage stability was examined by checking the changes in viscosity
at 23° C. and tackiness of an epoxy resin composition measured
before and after the exposure of the epoxy resin composition to the
conditions described below.

[0523] Exposed conditions

[0524] Temperature: 23° C.

[0525] Humidity: 50% RH

[0526] <Examination of Curability of Epoxy Resin Composition>

[0527] 13 g of an epoxy resin composition was weighed in an aluminum cup
having a diameter of 50 mm, the epoxy resin composition was heated in an
air heating furnace, and the feasibility of curing was checked.

[0528] Conditions for temperature elevation: temperature elevated from
room temperature to the curing temperature at a rate of 2° C./min

[0533] Each of the epoxy resin compositions thus prepared was poured
between two sheets of glass plates, with a spacer having a thickness of 2
mm or 3 mm disposed therebetween. The temperature was increased up to
110° C. or 135° C. at a rate of 2° C./min,
subsequently the temperature inside the furnace was maintained at
110° C. or 135° C., and the epoxy resin composition was
cured for 2 hours. Thereby, a cured plate of the epoxy resin composition
was produced.

[0534] <Measurement of Glass Transition Temperature of Cured
Product>

[0535] For the cured plates obtained in the above section <Production
of cured plate of epoxy resin composition>, the glass transition
temperatures (G'-Tg) were measured by a DMA method (Dynamic Mechanical
Analysis). Specifically, as illustrated in the graph of FIG. 2, log G'
was plotted against temperature, and the temperature determined from the
intersection between an approximating straight line for a flat region
before the transition of log G' and an approximating straight line for
the region where transition of G' occurs, was recorded as G'-Tg.

[0544] Production of a specimen and a test were carried out according to
the SENB (Single Edge Notched Bend) testing method according to ASTM
D5045, in an environment at a temperature of 20° C. and a humidity
of 50% RH (relative humidity). Each of the epoxy resin compositions of
Examples and Comparative Examples was cured under the same heating
conditions as the conditions for the examination of curability, and from
a cured resin plate having a thickness of 3 mm thus obtained, a small
piece having a predetermined dimension (27 mm×3 mm×6 mm) was
cut out. A notch was inserted in the small piece with a wet type diamond
cutter, and a razor that had been degreased in MEK (methyl ethyl ketone)
was caused to slide while the razor was pressed against an edge of the
notch, to form a pre-crack. Thus, a specimen was produced. The specimen
thus formed was subjected to a fracture toughness test with a universal
testing machine (manufactured by Instron, Inc., 4465).

[0545] The epoxy resin composition of Example 1 could be cured at
110° C., and the heat resistance of the cured product was
100° C. or higher, while KIc was 0.8 MPa/m0.5 or more. Thus,
the properties were all excellent.

[0546] Furthermore, even after the specimen was exposed to an environment
at 23° C. and 50% RH for one month, no change was observed in the
resin viscosity, and storage stability was also satisfactory.

[0548] In a 2-liter flask, 1000 g of MX-154, which is a master batch type
rubber particle-dispersed epoxy resin having the component (C) dispersed
in the epoxy resin of the component (A), was weighed, and then 65 g of
DY9577 as the component (B) was weighed and added thereto. While the
flask was heated in an oil bath at 60° C., the content of the
flask was stirred for 20 minutes and uniformly mixed. The flask was
removed from an oil bath, and the flask was left to cool until the
temperature of the content reached 40° C. or lower. Thus, an epoxy
resin composition of Example 2 was obtained.

[0549] <Preparation of Resin Composition of Example 3>

[0550] 2.00 kg of MX-113, which is a master batch type rubber
particle-dispersed epoxy resin having the component (C) dispersed in the
epoxy resin of the component (A), was weighed, and then 600 g of J-5800
as the component (C) was added thereto. The mixture was kneaded and
dispersed using a three-roll mill. Subsequently, in a 2-liter flask, 1.30
kg of this kneaded dispersion was weighed, and then 100 g of DY9577 as
the component (B) was weighed and added thereto. While the flask was
heated in an oil bath at 60° C., the content was stirred for 20
minutes and uniformly mixed. The flask was removed from the oil bath, and
the flask was left to cool until the temperature of the content reached
40° C. or lower. Thus, an epoxy resin composition of Example 3 was
obtained.

[0551] <Preparation of Resin Composition of Example 4>

[0552] In a 2-liter flask, 500 g of MX-154, which is a master batch type
rubber particle-dispersed epoxy resin having the component (C) dispersed
in the epoxy resin of the component (A), and 500 g of jER828 as the
component (A) were weighed, and then 70 g of DY9577 as the component (B)
was weighed and added thereto. While the flask was heated in an oil bath
at 60° C., the content of the flask was stirred for 20 minutes and
uniformly mixed. The flask was removed from an oil bath, and the flask
was left to cool until the temperature of the content reached 40°
C. or lower. Thus, an epoxy resin composition of Example 3 was obtained.

[0553] <Preparation of Resin Composition of Example 5>

[0554] In a 2-liter flask, 750 g of MX-113, which is a master batch type
rubber particle-dispersed epoxy resin having the component (C) dispersed
in the epoxy resin of the component (A), and 250 g of jER828 as the
component (A) were weighed, and then 100 g of DY9577 as the component (B)
was weighed and added thereto. While the flask was heated in an oil bath
at 60° C., the content of the flask was stirred for 20 minutes and
uniformly mixed. The flask was removed from an oil bath, and the flask
was left to cool until the temperature of the content reached 40°
C. or lower. Thus, an epoxy resin composition of Example 5 was obtained.

[0555] <Preparation of Resin Composition of Example 6>

[0556] In a 2-liter flask, 1 kg of MX-154, which is a master batch type
rubber particle-dispersed epoxy resin having the component (C) dispersed
in the epoxy resin of the component (A), was weighed, and then 100 g of
DY9577 as the component (B) was weighed and added thereto. While the
flask was heated in an oil bath at 60° C., the content of the
flask was stirred for 20 minutes and uniformly mixed. The flask was
removed from an oil bath, and the flask was left to cool until the
temperature of the content reached 40° C. or lower. Thus, an epoxy
resin composition of Example 6 was obtained.

[0557] <Preparation of Resin Composition of Example 7>

[0558] In a 2-liter flask, 400 g of MX-154 and 100 g of MX-416, which are
master batch type rubber particle-dispersed epoxy resins having the
component (C) dispersed in the epoxy resins of the component (A), and 150
g of jER828, 250 g of jER807, and 100 g of jER604 as the component (A)
were weighed, and then 100 g of DY9577 as the component (B) was weighed
and added thereto. While the flask was heated in an oil bath at
60° C., the content of the flask was stirred for 20 minutes and
uniformly mixed. The flask was removed from an oil bath, and the flask
was left to cool until the temperature of the content reached 40°
C. or lower. Thus, an epoxy resin composition of Example 7 was obtained.

[0559] <Preparation of Resin Composition of Comparative Example 2>

[0560] 500 g of jER828, 200 g of DICY7, and 75 g of DCMU99 were weighed in
a container, and the mixture was mixed using a spatula. This mixture was
kneaded using a three-roll mill, and thus a resin mixture A having DICY7
and DCMU99 uniformly dispersed in jER828 was obtained.

[0561] In a 2-liter flask, 900 g of jER828 was weighed, and then 155 g of
the resin mixture A previously prepared was weighed and added thereto.
This mixture was stirred and mixed for 20 minutes, and thereby a resin
composition of Comparative Example 2 was obtained.

[0562] <Preparation of Resin Composition of Comparative Example 3>

[0563] In a 2-liter flask, 100 g of jER1002 and 900 g of jER604 as the
component (A) were weighed, and while the flask was heated in an oil bath
at 120° C., the content of the flask was uniformly mixed by
stirring for 30 minutes. The flask was left to cool until the temperature
of the content reached 60° C. or lower. Furthermore, 60 g of
DY9577 as the component (B) was weighed and added to this 2-liter flask,
and while the flask was heated in an oil bath at 60° C., the
content was stirred for 20 minutes and uniformly mixed. The flask was
removed from the oil bath, and the flask was left to cool until the
temperature of the content reached 40° C. or lower. Thus, an epoxy
resin composition of Comparative Example 3 was obtained.

[0564] For the epoxy resin compositions obtained in Examples 2 to 7 and
Comparative Examples 2 and 3, storage stability and curability were
measured by the same methods as described above. Furthermore, composite
material-reinforced pressure vessels were produced using the respective
compositions, and the burst pressures were measured. The results are
presented in Table 2 and Table 3.

[0565] <Production of Composite Material-Reinforced Pressure Vessel>

[0566] A composite material-reinforced pressure vessel for evaluation was
produced by the following procedure.

[0567] A high strength carbon fiber manufactured by Grafil, Inc., product
name: 37-800 (tensile strength: 5300 MPa, tensile modulus: 255 GPa),
which was impregnated with an epoxy resin composition to a resin content
of 24% (that is, a tow prepreg produced according to the section
<Production of tow prepreg> described below), was wound around an
aluminum liner having an outer diameter of 160 mm and a length of 515 mm
(capacity 9 liters, see FIG. 1 for the shape) using a filament winding
apparatus. The aluminum liner used was made of a material obtained by
heat treating the aluminum material defined in JIS H4040 A6061-T6, and
the thickness of the body was about 3.3 mm.

[0568] The tow prepreg was wound around the aluminum liner after the
position was adjusted using a guide roll. First, for a first layer that
is brought into contact with the body of the aluminum liner, a hoop layer
forming an angle of 88.6° with respect to the direction of the
rotating axis was formed on the body to a thickness of 0.63 mm.
Thereafter, a helical layer for reinforcing the panels of the liner was
laminated at an angle of 14° with respect to the direction of the
rotating axis, and the tow prepreg was wound such that the thickness of
the fiber-reinforced resin layer of the body would be 2.5 mm. Meanwhile,
the thickness of the fiber-reinforced resin layer was determined by
measuring the outer diameter using vernier calipers.

[0569] The liner having the fiber-reinforced resin layer formed thereon by
the above procedure was removed from the filament winding apparatus and
was suspended in an air heating furnace, and the temperature inside the
furnace was increased to 110° C. at a rate of 2° C./min.
After it was confirmed that the surface temperature of the
fiber-reinforced resin layer reached 110° C., the temperature
inside the furnace was maintained at 110° C. for 2 hours, and thus
the epoxy resin composition was cured. Thereafter, the temperature inside
the furnace was cooled to 60° C. at a rate of 1° C./min,
and a composite material-reinforced pressure vessel (9-L tank) was
obtained.

[0570] <Production of Tow Prepreg>

[0571] A tow prepreg was produced using each of the epoxy resin
compositions obtained in Examples and Comparative Examples described
above, and a high strength carbon fiber manufactured by Grafil, Inc.,
product name: 37-800 (tensile strength: 5300 MPa, tensile modulus: 255
GPa).

[0572] First, the carbon fiber was heated to 50° C. to 100°
C., and the carbon fiber was spread to a width of 11 to 15 mm.

[0573] To the carbon fiber thus spread (hereinafter, simply referred to as
"carbon fiber bundle"), an epoxy resin composition adjusted to 65°
C. was quantitatively supplied using an epoxy resin composition supplying
apparatus, and the carbon fiber bundle was uniformly impregnated with the
epoxy resin composition using a resin impregnation apparatus composed of
heating rolls. As one of the impregnation means for uniformly
impregnating the reinforcing fiber bundle with the epoxy resin
composition, a method of moving the filaments in a transverse direction
was employed.

[0574] This was cooled to room temperature, and then was wound around a
bobbin.

[0575] <Method for Measuring Burst Pressure>

[0576] The pressure vessel was mounted on a hydraulic fracturing testing
machine, the pressure vessel was filled with water, and then hydraulic
pressure was exerted on the pressure vessel at a rate of pressure
increase of 15 MPa/min. The hydraulic pressure at the time when the
pressure vessel was burst was recorded, and this was designated as the
actually measured burst pressure of the pressure vessel.

[0577] Furthermore, for the hoop stress, it was assumed that there was no
resistance against the internal pressure of the liner, that is, the
stress in the diameter direction of the hoop layer in contact with the
liner and the burst pressure of the pressure vessel were equal, and it
was also assumed that the elastic modulus in the circumferential
direction of the helical layer was negligibly small, that is, the hoop
stress at the outermost layer surface of the hoop layer was zero.
Thereby, the hoop stress in an arbitrary hoop layer can be obtained by
the calculation formula for the hoop stress of a thick-walled cylinder as
described in Formula (1).

σ=(P×r12×(r22+r2))/(r2.t-
imes.(r22-r12)) Formula (1)

[0578] σ: Hoop stress (MPa) of thick-walled cylinder

[0579] P: Internal pressure (MPa) of pressure vessel

[0580] r: Arbitrary radius (mm) from the center in a cross-section
perpendicular to the axis of the pressure vessel

[0581] r1: Radius (mm) from the center in a cross-section
perpendicular to the axis of the pressure vessel to the inner wall of the
pressure vessel

[0582] r2: Radius (mm) from the center in a cross-section
perpendicular to the axis of the pressure vessel to the outer wall of the
pressure vessel.

[0583] Here, the tank internal pressure in a case in which the fracture
hoop stress of the hoop layer that is in contact with the liner, which is
calculated based on the actually measured burst pressure (actual value)
of a tank in which the thickness of the hoop layer measured as described
above is 0.63 mm, and the hoop stress of the hoop layer that is in
contact with the liner, of a tank having a hoop thickness of 2.80 mm are
equal, is designated as the burst pressure (calculated value). When the
burst pressure (calculated value) exceeded 158 MPa, which was a value
obtained by multiplying 70 MPa, which is a requirement for a composite
material-reinforced pressure vessel (9-L tank), by a safety ratio of 2.25
times, it was considered acceptable.

[0585] All the raw materials were weighed in a flask, and then while the
flask was heated in a water bath at 45° C. to 60° C., the
content of the flask was stirred until the raw materials fed to the flask
became sufficiently uniform under visual inspection. Thus, epoxy resin
compositions were obtained.

[0586] <Preparation of Resin Compositions of Examples 31 and 33>

[0587] The entire amount of the component (C) was dispersed in a portion
of a master batch of the component (A) and the component (C) using a
three-roll mill. The portion of the master batch of the component (A) and
the component (C) in which the entire amount of the component (C) was
dispersed, the remaining portion of the master batch of the component (A)
and the component (C), and the component (B) were weighed in a flask, and
then while the flask was heated in a water bath at 45° C. to
60° C., the content of the flask was stirred until the raw
materials fed to the flask became sufficiently uniform under visual
inspection. Thus, epoxy resin compositions were obtained.

[0588] <Preparation of Resin Compositions of Examples 10 and 22 to
25>

[0589] The entire amount of the component (C) was dispersed in a portion
of the component (A) using a three-roll mill. The portion of the
component (A) in which the entire amount of the component (C) was
dispersed, the remaining portion of the component (A), and the component
(B) were weighed in a flask, and then while the flask was heated in a
water bath at 45° C. to 60° C., the content of the flask
was stirred until the raw materials fed to the flask became sufficiently
uniform under visual inspection. Thus, epoxy resin compositions were
obtained.

[0591] The component (A), a master batch of the component (A) and the
component (C), and the component (D) were weighed in a flask, and then
while the flask was heated in an oil bath at 150° C. to
160° C., the content of the flask was stirred until the content
became sufficiently uniform under visual inspection. Thereafter, the
flask was removed from the oil bath, the flask was left to cool until the
temperature of the content reached 60° C. or lower, and the
remaining raw materials were weighed and added to the flask.
Subsequently, while the flask was heated in a water bath at 45° C.
to 60° C., the content of the flask was stirred until the content
became sufficiently uniform under visual inspection. Thus, epoxy resin
compositions were obtained.

[0593] The component (A) and the component (D) were weighed in a flask,
and then while the flask was heated in an oil bath at 150° C. to
160° C., the content of the flask was stirred until the content
became uniform. Thereafter, the flask was removed from the oil bath, the
flask was left to cool until the temperature of the content reached
60° C. or lower, and the remaining raw materials were weighed and
added to the flask. Subsequently, while the flask was heated in a water
bath at 45° C. to 60° C., the content of the flask was
stirred until the content became sufficiently uniform under visual
inspection. Thus, epoxy resin compositions were obtained.

[0595] In a portion of the component (A), or/and a portion of a master
batch of the component (A) and the component (C), the other raw materials
were dispersed using a three-roll mill. The portion of the component (A),
or/and the portion of the component (A) and the component (C), in which
the other raw materials were dispersed, and the remaining portion of the
component (A), or/and the remaining portion of the component (A) and the
component (C) were weighed in a flask, and then while the flask was
heated in a water bath at 45° C. to 60° C., the content of
the flask was stirred until the raw materials fed to the flask became
sufficiently uniform under visual inspection. Thus, epoxy resin
compositions were obtained.

[0597] In a portion of the component (A), or a portion of a master batch
of the component (A) and the component (C), 2P4MHZ which was another raw
material was dispersed using a three-roll mill. The portion of the
component (A), or the master batch of the component (A) and the component
(C), in which 2P4MHZ was dispersed, the remaining portion of the
component (A), or the remaining portion of the master batch of the
component (A) and the component (C), and HX-3722 which was another raw
material, were weighed in a flask. Subsequently, while the flask was
heated in a water bath at 45° C. to 60° C., the content of
the flask was stirred until the raw materials fed to the flask became
sufficiently uniform under visual inspection. Thus, epoxy resin
compositions were obtained.

[0598] <Preparation of Resin Composition of Reference Example 1>

[0599] In jER828 as the component (A), other raw materials DICY7 and
DCMU99 were dispersed using a three-roll mill. Furthermore, MX-113 which
was a master batch of the component (A) and the component (C), and jER807
and YDF-2011 as the component (A) were weighed in a flask, and while the
flask was heated in an oil bath at 120° C. to 130° C., the
content of the flask was stirred until the content became uniform.
Thereafter, the flask was removed from the oil bath, and the flask was
left to cool until the temperature of the content reached 60° C.
or lower. jER828 as the component (A) in which other raw materials DICY7
and DCMU99 were dispersed, was weighed and added to the flask.
Subsequently, while the flask was heated in a water bath at 55° C.
to 65° C., the content of the flask was stirred until the content
became uniform. Thus, an epoxy resin composition was obtained.

[0600] <Preparation of Resin Composition of Reference Example 2>

[0601] The component (A) and the component (D) were weighed in a flask,
and then while the flask was heated in an oil bath at 170° C. to
180° C., the content of the flask was stirred until the content
became uniform. Thereafter, the flask was removed from the oil bath, the
flask was left to cool until the temperature of the content reached
60° C., and the remaining raw materials were weighed and added to
the flask. Subsequently, while the flask was heated in a water bath at
60° C. to 70° C., the content of the flask was stirred
until the content became uniform. Thus, an epoxy resin composition was
obtained.

Examples 8 to 11 and Comparative Examples 4 to 10

[0602] The various compositions described in Table 4 were prepared
according to the Examples and Comparative Examples described above.

[0603] Pressure vessels were produced using the compositions thus
obtained, by the method of <Production of composite
material-reinforced pressure vessel>. However, a liner having a
fiber-reinforced resin layer formed thereon was removed from the filament
winding apparatus and suspended in an air heating furnace, and the
temperature inside the furnace was increased to the curing temperature
described in Table 4 at a rate of 2° C./min. After it was
confirmed that the surface temperature of the fiber-reinforced resin
layer reached the curing temperature, the temperature inside the furnace
was maintained at the curing temperature for 2 hours, and thus the epoxy
resin composition was cured.

[0604] For the pressure vessels thus obtained, the burst pressures were
measured by the method of <Method for measuring burst pressure>.
The results are presented in Table 4.

[0605] As can be seen from these Examples and Comparative Examples, when
only the component (A): epoxy resin is used, or when the component (A):
epoxy resin and the component (B): a boron halide-amine complex are used
in combination, a pressure vessel exhibiting a sufficient burst pressure
cannot be obtained. When the component (A): epoxy resin, the component
(B): a boron halide-amine complex, and the component (C): rubber
particles are used in combination, a pressure vessel exhibiting a
sufficient burst pressure can be obtained.

Examples 12 to 18 and Comparative Examples 11 to 13

[0606] The various compositions described in Table 5 were prepared
according to the Examples and Comparative Examples described above.

[0607] Cured plates were produced using the compositions thus obtained,
according to the above section <Production of cured plate of epoxy
resin composition>. For the cured plates thus obtained, G'-Tg was
measured by the method of <Measurement of glass transition temperature
of cured product>. The results are presented in Table 5.

[0608] The state of the cross-section of the cured plates was observed
using the cured plates produced in this manner, by the method described
in the following section <Observation of sea-island phase separation
structure of cured product>.

[0610] A cured product was embedded in a embedding resin (manufactured by
Nisshin EM Corp., TECHNOVIT 4000), and the cured product was polished
using a polishing machine (manufactured by Refine Tech Co., Ltd.,
ADM-122). Thus, a cured product cross-section was obtained.

[0611] The cross-section of the cured product was observed by LSM (laser
scan microscopy, "Nanosearch Laser Microscope LEXT3500" manufactured by
Olympus Corp.), and images were taken after the conditions were adjusted
to the magnification ratio and brightness enabling observation.

[0612] As can be seen from these Examples and Comparative Examples, when
the amount of incorporation of the component (B): a boron halide-amine
complex is adjusted to usually 8 parts by mass or more, preferably 9
parts by mass or more, and usually to 20 parts by mass or less,
preferably 18 parts by mass or less, and more preferably 17 parts by mass
or less, relative to 100 parts by mass of the component (A) included in
the epoxy resin composition of the present invention, a cured product
having a high G'-Tg value can be obtained.

Examples 19 to 34 and Comparative Example 14

[0613] The various compositions described in Table 6 were prepared
according to the Examples and Comparative Examples described above.

[0614] Pressure vessels were produced using the compositions thus
obtained, by the method of <Production of composite
material-reinforced pressure vessel>. However, a liner having a
fiber-reinforced resin layer formed thereon was removed from the filament
winding apparatus and suspended in an air heating furnace, and the
temperature inside the furnace was increased to the curing temperature
described in Table 6 at a rate of 2° C./min. After it was
confirmed that the surface temperature of the fiber-reinforced resin
layer reached the curing temperature, the temperature inside the furnace
was maintained at the curing temperature for 2 hours, and thus the epoxy
resin composition was cured.

[0615] For the pressure vessels thus obtained, the burst pressures were
measured by the method of <Method for measuring burst pressure>.
The results are presented in Table 6.

[0616] Meanwhile, for Example 19, an LSM photograph of a cross-section of
the cured plate produced using the composition thus obtained is shown in
FIG. 3.

[0617] As can be seen from these Examples and Comparative Examples, when
the epoxy resin composition of the present inventions are used, pressure
vessels exhibiting high burst pressures can be obtained.

Examples 35 to 37 and Reference Examples 1 and 2

[0618] The various compositions described in Table 7 were prepared
according to the Examples and Comparative Examples described above.

[0619] (Meanwhile, the epoxy resin compositions of Example 35 and Example
1, Example 36 and Example 28, and Example 37 and Example 27 are the same
compositions.)

[0620] Tow prepregs were produced using the epoxy resin compositions thus
obtained, according to the <Production of tow prepreg>, and
pressure vessels were produced according to the <Production of
composite material-reinforced pressure vessel>.

[0621] At the time of the <Production of composite material-reinforced
pressure vessel>, <Evaluation of reelability of tow prepreg> and
<Evaluation of processability of tow prepreg> as described below
were carried out.

[0622] <Evaluation of Reelability of Tow Prepreg>

[0623] Upon the production of a pressure vessel, when there was a problem
of filament breakage that single fibers (filaments) of the reinforcing
fiber bundle were entangled with the epoxy resin composition on the
bobbin and were broken, the sample was rated as "B (unacceptable
reelability)"; and when there was no such problem, the sample was rated
as "A (acceptable reelability)".

[0624] <Evaluation of Processability of Tow Prepreg>

[0625] Upon production of a pressure vessel, when fluff generation was
confirmed on the tow prepreg surface due to scraping with the guide roll
or the like, the sample was rated as "B (unacceptable processability)";
and when no fluff generation was confirmed, the sample was rated as "A
(acceptable processability)".

[0626] Furthermore, cured plates were produced using the epoxy resin
compositions thus obtained, in the same manner as in Examples 12 to 18
and Comparative Examples 11 to 13, and the surface state was observed.
The results are presented in Table 7.

[0627] When the viscosity of the epoxy resin composition used was adjusted
to 300 Pas or less, a tow prepreg having excellent reelability and
processability could be obtained. Furthermore, since the viscosity of the
epoxy resin composition of Reference Example 1 was 300 Pas or less, the
tow prepreg had excellent reelability and processability; however, it
should be noted that since the component (B) was different from that of
the present invention, the burst pressure of the pressure vessel was
insufficient.

Example 38 and Comparative Example 15

Example Corresponding to Second Embodiment of Present Invention

[0628] The various compositions described in Table 8 were prepared
according to the Examples and Comparative Examples described above.

[0629] Tow prepregs were produced using the epoxy resin compositions thus
obtained, according to the <Production of tow prepreg>, and
pressure vessels were produced according to the <Production of
composite material-reinforced pressure vessel>.

[0630] For the pressure vessels thus obtained, the burst pressure was
measured by the method of <Method for measuring burst pressure>.

[0631] Furthermore, cured plates were produced using the epoxy resin
compositions thus obtained, in the same manner as in Examples 12 to 18
and Comparative Examples 11 to 13, and the surface state was observed.

[0633] According to the present invention, an epoxy resin composition
which has excellent storage stability, produces a cured product having
excellent heat resistance and toughness, and can be suitably used in
direct molding such as FW molding as well as in intermediate materials
such as a tow prepreg; a tow prepreg having excellent reelability,
processability and drape properties; and a pressure vessel having high
pressure resistance performance, can be provided. Therefore, the present
invention is industrially highly useful.

Patent applications by Akihiro Ito, Toyohashi-Shi JP

Patent applications by Mitsubishi Rayon Co., Ltd.

Patent applications in class Polymer derived from ethylenic reactants only

Patent applications in all subclasses Polymer derived from ethylenic reactants only